# Shared Flashcard Set

## Details

Tests from the year
162
Physics
05/29/2009

Term
 Suppose than an object travels from one point in space to another. How can you compare the displacement and the distance traveled?
Definition
 The displacement is either less than or equal to the distance traveled.
Term
 A new car manufacturer advertises that their car can go from 0 to 60 in 8 seconds. This is a description of
Definition
 Average acceleration
Term
 An object moving in the positive x-axis experiences an acceleration of 2.0 m/s^2. This means the object is...
Definition
 increasing in velocity by 2.0m/s^2 in every second
Term
 An object is moving with constant non-zero velocity in the positive x-axis. The position versus time graph of this object is...
Definition
 a horizontal straight line
Term
 If the position versus time graph of an object is a horizontal line, the object is...
Definition
 moving with constant non-zero speed
Term
 An object moves 15m North and then 11m South. Find both the distance traveled and the magnitude of the displacement vector.
Definition
 26m, 6m
Term
 A boat can move at 30kmph in still water. How long will it take to move 12 km upstream in a river flowing 6kmph?
Definition
 20 minutes
Term
 55mph is how many m/s? (1mi = 1609 m)
Definition
 25 m/s   Explanation: 8849m/3600s = 24.5m/s
Term
 What must be your average speed in order to travel 350 km in 5.15 hours?
Definition
 68km/h   Explanation: 350km/5.15 = 67.9km/h
Term
 A runner ran the marathon approximatley 42km in 2 hours and 57 minutes. What is the average speed of the runner in m/s?
Definition
 3.95 m/s   Explanation: 42km/2hr57min 42000m/10320s = 4.07m/s^2
Term
 If you are driving 72km/h along a straight road and you look to the side for 4 s, how far do you travel during this inattentive period?
Definition
 80m   Explanation: 72000m/3600s = 20m/s
Term
 A polar bear starts at the north pole. It travels 1km South, then 1 km East, then 1km NOrth, then 1 km West to return to its starting point. This trip takes 45 minutes. What was the bear's avergae velocity
Definition
 5.3 km/h   Explanation: 4km/45 min 4/.75 = 5.3km/h
Term
 Suppose a car is moving in a straight line and steadily increases its speed. It moves from 35km/h to 40km/h the first second. And from 40km.h to 45km/h the next second. What is the car's acceleration?
Definition
 5km/hxs   Explanation: (40-35)/1 = 5km/h
Term
 When something falls to the ground it accelerates. This acceleration is called the acceleration due to gravity and is symbolized by the letter "g." What is the value of "g" on Earth's surface?
Definition
Term
 A car accelerates at 2m/s^2. Assuming the car strats from rest, how much time does it need to accelerate to a speed of 20m/s?
Definition
 10 seconds   Explanation: t = v/a t = 20/2 t = 10
Term
 A train moves down the track with a constant velocity. What might the area under the velocity versus time graph tell us about the motion of the train?
Definition
 the acceleration
Term
 As an object falls freely in a vaccum, it's
Definition
 velocity increases
Term
 In the absence of air resistance objects fall at constant
Definition
 acceleration
Term
 A ball is thrown upwards and caught when it comes back down. In the absence of air resistance, the speed of the ball when caught would be
Definition
 the same as the speed it had when thrown upwards
Term
 Suppose an object is in free fall. Each second the object falls
Definition
 a larger distance than in the second before
Term
 Consider drops of water leaking from a water faucet. As the drops fall they
Definition
 get farther apart
Term
 A ball tossed vertically upward rises, reaches its highest point, and then falls back to its starting point. During this time the acceleration of the ball is always
Definition
 directed downward
Term
 When a basketball player jumps to make a shot, once the feet are off the floor the jumper's acceleration
Definition
 is "g", no more, no less
Term
 A ball is thrown straight up. At the top of its path its instantaneous speed is
Definition
 0 m/s
Term
 A ball is thrown straight up. At the top of its path, its acceleration is
Definition
Term
 If a freely falling object were somehow equipped with a speedometer, its speed reading would increase each second by
Definition
Term
 A freely falling object strats from rest. After falling for 6 seconds it will have a speed of about
Definition
 60m/s
Term
 Acceleration is defined as the change in
Definition
 velocity divided by the time interval
Term
 Suppose you are in a car that is going around a curve. The speedometer reads a constant 30m/h. What is not true?
Definition
Term
 A car starts from rest and after 7 seoncds it is moving 42m/s. What is the car's average acceleration?
Definition
 6m/s^2   Explanation: a = v/t a = 42/7 a = 6
Term
 When representing velocity as a vector
Definition
 1.The direction of the arrow shows the direction of motion 2. The length of the arrow represents the speed 3.The length of the arrow is drawn to a suitable scale ALL OF THESE ABOVE
Term
 In the absence of air friction, the horizontal component of a projectile's velocity doesn't change as the projectile moves
Definition
 Always True
Term
 A ball is thrown into the air at some angle. At the very top of the ball's path, it's velocity is
Definition
 entirely horizontal
Term
 In the absence of air resistance, at what other angle will a thrown ball go the same distance as one thrown at an angle of 75 degrees?
Definition
 15 degrees
Term
 When you sit on a chair, the resultant force on you is
Definition
 zero
Term
 In the absence of an external force, a moving object will
Definition
 move with constant velocity
Term
 You are standing in a moving bus, facing forward, and you suddenly fall forward as the bus comes to an immediate stop. What force caused you to fall forward?
Definition
Term
 Which of Newton's laws best explains why motorists should buckle up?
Definition
 The 1st Law
Term
 When the rocket engines on the starship NO-PAIN-NO-GAIN are suddenly turned off, while traveling in empty space, the straship will
Definition
 move with constant speed
Term
 In the diagram shown, the unknown vector is... [image] [image] [image]
Definition
 B - A
Term
 A 10kg mass slides down a flat hill that makes an angle of 10 degrees with the horizontal. If friction is negligible, what is the resultant force on the sled?
Definition
 17N   Explanation: n = 1.7(10) n = 17
Term
 [image] A traffic light of weight 100N is supported by two ropes as shown in Fig.4-2. What are the tensions in the ropes?
Definition
 83 N   Explanation: sin37 = 100/h h = 83
Term
 What is the speed of an object at rest?
Definition
 0.0 m/s
Term
 Which of the following situations represents a negative displacement? (Assume positive position is measured vertically upward along a y-axis.)
Definition
 A cat jumps from a tree limb to the ground.
Term
 Which of the following units is thet SI unit of velocity?
Definition
 meter per second
Term
 [image] Position   In the graph above, what is the correct description of any location to the left of the zero?
Definition
 negative position
Term
 In the graph above, a toy car rolls from +3m to +5m. Which of the following statements is true?
Definition
 xi = +3m
Term
 Suppose you are given a positon versus time graph. The slope of a line drawn tangent to a point on the curve of this graph describes what quantity?
Definition
 instantaneous velocity
Term
 Which of the following line segments on a position versus time graph is physically impossible?
Definition
 a vertical line
Term
 Acceleration is defined as
Definition
 the rate of changing velocity
Term
 Which of the following is the equation for acceleration?
Definition
 a = Δv/Δt
Term
 What is the SI unit of acceleration?
Definition
 m/s2
Term
 If you know the aaceleration of a car, its initial veloctiy, and the time interval, which of the following can you predict?
Definition
 1. The direction of the car's final velocity 2. the magnitude of the car's final velocity 3. the displacement of the car ALL OF THE ABOVE
Term
 When a car's velocity is positive and its acceleration is negative, what is happening to the car's motion?
Definition
 the car slows down
Term
 When a car's velocity is negative and its acceleration is negative, what is happening to the car's motion?
Definition
 the car speeds up
Term
 Which of the following line segments on a velocity versus time graph is physically impossible?
Definition
 vertical line
Term
 The motion of a ball on an inclined plane is described by the equation: Δx = 1/2a(Δt)2. Which of the following quantities must have a value of zero?
Definition
 vi
Term
 Acceleration due to gravity is also called
Definition
 free-fall acceleration
Term
 Which of the following statements applies to the motion of a ball rising and then falling in free fall?
Definition
 I. The ball has constant acceleration as it moves upward. II. The ball has constant acceleration at the top of its path. III. The ball has constant acceleration as it moves downward. I, II, and III
Term
 A baseball catcher throws a ball vertically upward and catches it in the same spot as it returns to the mitt. At what point in the ball's path does it experience zero velocity and nonzero acceleration at the same time?
Definition
 at the top of its path
Term
 When there is no air resistance, obejcts of different masses dropped from rest
Definition
 fall with equal accelerations and with equal displacements
Term
 Objects that are falling toward Earth in free fall move
Definition
 faster and faster
Term
 Which would hit the ground first if dropped from the same height in a vacuum-- a feather or a metal bolt?
Definition
 They would hit the ground at the same time
Term
 Which would fall with greater acceleration in a vacuum--a leaf or a stone?
Definition
 They would accelerate at the same rate.
Term
 Two students are standing on a fire escape, one twice as high as the other. Simultaneously, each drops a ball. If the first ball strikes the ground at time Δt1, when will the second ball strike the ground?(Disregard air resistance. Assume a=-g=-9.81m/s2)
Definition
 Δt2 = √2Δt2
Term
 Which of the following is a physical quality that has a magnitude but no direction?
Definition
 scalar
Term
 Which of the following is a physical quality that has both magnitude and direction?
Definition
 vector
Term
 Identify the following quantites as scalar or vector: the mass of an object, the number of leaves on a tree, wind velocity.
Definition
 scalar, scalar, vector
Term
 Identify the following quantites as scalar or vector: the speed of a snail, the time it takes to run a mile, the free-fall acceleration.
Definition
 scalar, scalar, vector
Term
 For the winter, a duck flies 10m/s  due south against a gust of wind with a speed of 2.5m/s. What is the resultant velocity of the duck?
Definition
 7.5m/s south
Term
 Multiplying or dividing vectors by scalars results in
Definition
 vectors
Term
 A car travels downa road at a certain velocity, vcar. The driver slows down so that the car is traveling only half as fast as before. Which of the following is the correct expression for the resulting velocity?
Definition
 1/2vcar
Term
 A student walks from the door of the house to the end of the driveway and realizes that he missed the bus. The student runs back to the house, traveling three times as fast. Which of the following is the correct expression for the return velocity if the initial velocity is vstudent.
Definition
 -3vstudent
Term
 Which of the following is the best coordinate system to analyze a painter climbing a ladder at an angle of 60dgrs to the ground?
Definition
 x-axis: horizontal along the ground; y-axis: up and down
Term
 An ant on a picnic table travels 3 x 103 cm eastward, then 25cm northward, and finally 15cm westward. What is the magnitude of the ant's displacement relative to its original position?
Definition
 29cm
Term
 In a coordinate system, a vector is oriented at angle θ with respect to the x-axis. The x component of the vector equals the vector's magnitude multiplied by which trigonometric function?
Definition
 cosθ
Term
 In a coordinate system, a vector is oriented at angle θ with respect to the x-axis. The y component of the vector equals the vector's magnitude multiplied by which trigonometric function?
Definition
 sinθ
Term
 Find the resultant of these two vectors:2 x 102 units due east and 4 x 102 units 30dgrs north of west.
Definition
 248 units, 53.9dgrs north of west
Term
 Which of the following is an example of projectile motion?
Definition
 a thrown baseball
Term
 Which of the following is not an example of projectile motion?
Definition
 a hot-air balloon drifting toward Earth
Term
 What is the path of a projectile (in the absence of friction)?
Definition
 a parabola
Term
 A passenger on a bus moving east sees a man standing on a curb. From the passenger's perspective, the man appears to
Definition
 move west at a speed that is equal to the bus's speed
Term
 A piece of chalk is dropped by a teacher walking at a speed of 1.5m/s. From the teacher's perspective, the chalk appears to fall
Definition
 straight down
Term
 A jet moving at 500km/h due east is in a region where the wind is moving at 120km/h in a direction 30dgrs north of east. What is the speed of the aircraft relative to the ground?
Definition
 606.9 km/h
Term
 A force does not work on an object if a component of the force
Definition
 is parallel to the displacement of the object
Term
 Work is done when
Definition
 the displacement is not zero
Term
 Formula for work?
Definition
 W=Fd
Term
 If the sign of work is negative...
Definition
 the displacement is in the direction opposite the force
Term
 IN which of the following scenarios is work done?
Definition
 A car decelerates while traveling on a flat stretch of road
Term
 In which of the following scenarios is no net work done?
Definition
 a car travels at a constant speed on a flat road
Term
 A child moving at constant velocity carries a 2N ice-cream cone 1m across a level surface. What is the net work done on the ice-cream cone?
Definition
 0 J
Term
 A worker does 25 J of work lifting a bucket, then sets the bucket back down in the same place. What is the total net work done on the bucket?
Definition
 0 J
Term
 A construction worker pushes a wheelbarrow 5m with a horizontal force of 50N. How much work is done by the worker on the wheelbarrow?
Definition
 250 J
Term
 Which of the following energy forms is associated with an object in motion?
Definition
 kinetic energy
Term
 Which of the following energy forms is associated with an object due to its position?
Definition
 potential energy
Term
 Ball A has triple the mass and speed of ball B. What is the ratio of the kinetic energy of ball A to ball B?
Definition
 27
Term
 If friction is the only force acting on an object during a given physical process, which of the following assumptions can be made in regard to the object's kinetic energy?
Definition
 the kinetic energy decreases
Term
 the main difference between kinetic energy and potential energy is that
Definition
 kinetic energy invovles motion and potential energy involves position
Term
 gravitational potential energy is always measured in relation to
Definition
 a zero level
Term
 Which of the following is a true statement about the conservation of energy?
Definition
 mechanical energy is always conserved
Term
 Why doesn't the principle of mechanical energy conservation hold in situations when frictional forces are present?
Definition
 kinetic energy is not completely converted to a form of potential energy
Term
 Which of the following is the rate at which energy is transferred?
Definition
 power
Term
 Which of the following equations can be used to directly calculate an object's momentum, p?
Definition
 p = mv
Term
 What are the SI units for momentum?
Definition
 kgxm/s
Term
 When comparing the momentum of two moving objects, which of the following is correct?
Definition
 The less massive object will have less momentum if the velocities are the same
Term
 Which of the following has the greatest momentum?
Definition
 a tortoise with a mass of 275kg moving at velocity of 0.55m/s
Term
 A person sitting in a chair with wheels stands up, causing the chair to roll backward across the floor. The momentum of the chair
Definition
 was zero while stationary and increased when the person stood
Term
 Which of the following equations can be used to directly calculate the change in an object's momentum?
Definition
 Δp = FΔ.t
Term
 If a force is exerted on an object, which statement is true?
Definition
 A small force applied over a long time interval can produce a large change in the object's momentum
Term
 Which of the following situations is an example of a visible change in momentum?
Definition
 A baseball is hit by a bat
Term
 Which of the following situations is an example of a significant change in momentum?
Definition
 a tennis ball is hit into a net
Term
 The impulse experienced by a body is equivalent to the body's change in
Definition
 momentum
Term
 Which of the following statements properly relates the variables in the equation FΔt = Δp?
Definition
 A large constant force acting over a long time interval causes a large change in momentum.
Term
 A soccer ball collides with another soccer ball at rest. The total momentum of the balls
Definition
 remains constant
Term
 In a two body collision
Definition
 momentum is always conserved
Term
 A player catches a ball. Consider the action force to be the impact of the ball against the player's glove. What is the reaction to this force?
Definition
 the force the glove exerts on the ball
Term
 an unfortunate bug splatters against the windshield of a moving car. Compared to the deceleration of the car, the deceleration of the bug is
Definition
 larger
Term
 Earth pulls on the moon and similarly the moon pulls on Earth. This is evidence that the
Definition
 1. Earth and moon are simply pulling on each other 2. Earth's and moon's pulls comprise an action-reaction pair   BOTH OF THESE
Term
 A rocket is able to accelerate in the vacuum of space when it fires its engines. The force that propels the rocket is the force
Definition
 of the exhaust gases on the rocket
Term
 Your friend says that the heavyweight champion of the world cannot exert a force of 95N on a peice of tissue paper with his best punch. The tissue paper is held in midair, no wall and no tricks.
Definition
 You agree that it can't be done.
Term
 Suppose two people, one having three times the mass of the other, pull on opposite sides of a 20 meter rope while on frictionless ice. After a brief time, they meet. The more  massive person slides a distance of...
Definition
 5m
Term
 In the absence of an external force, a moving object will
Definition
 move with constant velocity
Term
 A rocket moves through empty space in a straight line with constant speed. It is far from the gravitational effect of any star or planet. Under these conditions, the force that must be applied to the rocket in order to sustain its motion is
Definition
 zero
Term
 A constant net force acts on an object. Describe the motion of the object
Definition
 constant acceleration
Term
 The acceleration of an object in inversely proportional to
Definition
 its mass
Term
 A net force F acts on a mass m and produces an acceleration s. What acceleration results if a net force 2F acts on mass 4m?
Definition
 2a
Term
 The time for one cycle of a periodic process is called the
Definition
 period
Term
 For a periodic process, the number of cycles per unit time is called the
Definition
 frequency
Term
 For vibrational motion, the maximum displacement from the equilibrium point is called the
Definition
 amplitude
Term
 A simple pendulum consists of mass M attatched to a weightless string of length L. For this system, when undergoing small oscillations
Definition
 the frequency is independent of the mass M
Term
 When the mass of a simple pendulum is tripled, the time required for one complete vibration
Definition
 does not change
Term
 What happens to a simple pendulum's frequency if both its length and mass are increased?
Definition
 it decreases
Term
 Simple pendulum A swings back and forth at twoce the frequency of simple pendulum B. Which statement is correct?
Definition
 The length of B is four times the length of A
Term
 If you take a given pendulum to the Moon, where the acceleration of gravity is less than on Earth, the resonant frequency of the pendulum will
Definition
 decrease
Term
 In a wave, the maximum displacement of points of the wave from equilibrium is called the wave's
Definition
 amplitude
Term
 The distance between successive crests on a wave is called the wave's
Definition
 wavelength
Term
 The number of crests of a wave passing a point per unit time is called the wave's
Definition
 frequency
Term
 For a wave, the frequency times the wavelength is the wave's
Definition
 speed
Term
 The frequency of a wave increases. What happens to the distance between successive crests if the speed remains constant?
Definition
 it decreases
Term
 In seismology, the S is a transverse wave. As an S wave travels through the Earth, the relative motion between the S wave and the particles is
Definition
 perpendicular
Term
 Two wave pulses with equal opposite amplitudes pass eachother on a string, one is traveling toward the right and the other toward the left. At the point that they occupy the same region of space at the same time
Definition
 constructive interference occurs
Term
 Two wave pulses pass eachother on a string. The one traveling toward the right has a positive amplitude, while the one traveling toward the left has an equal amplitude in the negative direction. At the point that they occupy the same region of space at the same time
Definition
 destructive interference occurs
Term
 When obeject is moving with uniform circular motion, the object's tangential speed
Definition
 is constant
Term
 When an object is moving with uniform circular motion, the centripetal acceleration of the object
Definition
 is directed toward the center of motion
Term
 What is the term for the net force directed toward the center of an object's circular path?
Definition
 centripetal force
Term
 Which of the following can be centripetal force?
Definition
 1.friction 2.gravity 3.tension ALL OF ABOVE
Term
 The centripetal force on an object in circular motion is
Definition
 in the plane of the object's motion and perpendicular to the tengential speed
Term
 When a car makes a sharp left turn, what causes the passengers to move toward the right side of car?
Definition
 centrifugal force
Term
 When calculating the gravitational force between two extended bodies, you should measure the distance
Definition
 from the center of each body
Term
 According to Kepler's laws of planetary motion
Definition
 if Δt1 = Δt2, then A1 = A2
Term
 How would the speed of Earth's orbit around the sun change if Earth's distance from the sun increased by 4 times?
Definition
 It would decrease by a factor of 2
Term
 How would the speed of Earth's orbit around the sun change if Earth's mass increased by 4 times?
Definition
 it would increase by a factor of 2
Term
 Is it possible for an object moving with a constant speed to accelerate? Explain.
Definition
 Yes, although the speed is constant, the direction of velocity can be changing.
Term
 An object moves in a circular path at a constant speed. Compare the direction of the object's velocity and acceleration vectors.
Definition
 The vectors are perpendicular
Term
 A car goes around a curve of radius r at a constant speed v. Then it goes around the same curve at half of the original speed. What is the centripetal force on the car as it goes around the curve for the second time, compared to the first time?
Definition
 one-fourth as big
Term
 Is it possible for an object moving around a circular path to have both centripetal anf tengential acceleration?
Definition
 Yes, this is possible if the speed is changing.
Term
 Two objects attract each other gravitationally. If the distance between their centers is cut in half, the gravitational force
Definition
Term
 Compared to its mass on Earth, the mass of an object on the Moon is
Definition
 the same
Term
 Suppose a satellite were orbiting the Earth just above the surface. What is its centripetal acceleration?
Definition
 equal to g
Term
 A hypothetical planet has a mass of half that of the Earth and a radius of twice that of the Earth. What is the acceleration due to gravity on the planet in terms of g, the acceleration due to gravity at Earth?
Definition
 g/8
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