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Physic's
Physic's exam 1
65
Physics
Undergraduate 2
03/21/2010

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Term
average speed
Definition
distance traveled/time taken

d/t
Term
distance traveled
Definition
average speed X time taken
Term
Velocity equal speed with a direction
Definition
Term
average velocity
Definition
change in position/time taken
Term
average acceleration
Definition
change in velocity/time taken
Term
the velocity of an object remains constant unless an unbalanced for
Definition
Newtons 1st law
Term
kinetic energy
Definition
KE=1/2mv^2
Term
What is the kinetic energy of an 86 kg sprinter running at 11 m/s?
Definition
5203 J
formla: KE=1/2mv^2
Term
work
Definition
work=forceXdistance moved
Term
gravitional potential energy
Definition
GPE= (mass)(gravity)(height)
Term
mechanical energy
Definition
is the same as KE+GPE

witch is =1/2mv^2+mgh
Term
power
Definition
energy converted/time taken
Term
A 0.5 kg air-hockey puck is initially at rest. What will its kinetic energy be after a net force of 0.6 N acts on it for a distance of 0.4 m?
Definition
.24 J
Term
A 15 N block lifted straight upward by a hand applying a force of 15 N has an initial kinetic energy of 8 J. If the block is lifted 2 m, how much work does the hand do?

What is the block's final kinetic energy?
Definition
30 J

30J
Term
The Earth, which orbits the Sun in an elliptical path, reaches its closest point to the Sun on about January 4 each year. Will the work done by the gravitational force of the Sun on the Earth be positive, negative, or zero over the next 6 months?


Will the work done be positive, negative, or zero over the next year?
Definition
The work done will be negative

The work done will be zero
Term
A woman with a mass of 65 kg climbs a set of stairs that are h = 2 m high. How much gravitational potential energy does she gain?
Definition
1300 J
Term
A baseball (mass = 145 g) is thrown straight upward with kinetic energy 10.15 J.
(a) When the ball has risen 7 m, find the work done by gravity. (Take g = 10 m/s2)

(b) Find the ball's kinetic energy.

(c) Find the ball's speed.
Definition
(a)-10.15 J

(b)0 J

(c)0 J
Term
What is the gravitational potential energy of a ball with a weight of 58 N when it is sitting on a shelf 1.8 m above the floor?
Definition
104.4 J
Term
If a 0.6 kg ball is dropped from a height of 9 m, what is its kinetic energy when it hits the ground?
Definition
54 J
Term
Rotational acceleration
Definition
a=w/t
ex. 200rpm-500rpm/60mins
ans= -5rpm/mins
Term
Rotational acceleration
(remember change the sign to the opposite)
Definition
Term
1 radian is equal to...
Definition
57 degrees
Term
torque
Definition
radius X force
Term
The angular velocity of an object remains constant unless acted on by an unbalanced torque
Definition
Newtons 1st law of rotation
Term
The net torque on an object is equal to its rotational inertia times it rotational acceleration
Definition
Newtons 2nd law of rotation
Term
formula for rotational kinetic energy
is same as the one for kinetic energy
Definition
Term
angular momentum
Definition
rotational inertia X rotational speed
Term
If the beaters on a Mixmaster make 890 revolutions in 3 minutes, what is the average rotational speed of the beaters? Express your answer in both revolutions per minute and revolutions per second.
Definition
296.6 rev/min
4.94 rev/s
Term
What is the rotational speed of the minute hand on a clock?
Definition
2.78e-4 rev/s
Term
If the rotational speed of a CD changes from 700 rpm to 275 rpm as it plays 30 minutes of music, what is the CD's average rotational acceleration?
Definition
-14.16 rev/min2
Term
You are holding a 30 kg dumbbell straight out at arm's length. Assuming your arm is 0.72 m long, what torque is the dumbbell exerting on your shoulder?
Definition
216 N·m
(just add a decimal point)
Term
Two children with masses of 21 and 43 kg are sitting on a balanced seesaw. If the lighter child is sitting 3 m from the center, where is the heavier child sitting?
Definition
1.46 m from the center
(set up a ratio)
Term
What mass would you hang on the right side of the system in the figure to balance it -- that is, to make the clockwise and counterclockwise torques equal? (Let x1 = 36 cm and x2 = 20 cm.)
Definition
90 g
Term
A child with a mass of 55 kg is riding on a merry-go-round. If the child has a speed of 3 m/s and is located 1.3 m from the center of the merry-go-round, what is the child's angular momentum?
Definition
214.5 kg·m2/s
Term
the laws of physics are the same in all inertail reference systems
Definition
principle of relativity
Term
A spring gun fires a ball horizontally at 12 m/s. It is mounted on a flatcar moving in a straight line at 25 m/s.
(a) Relative to the ground, what is the horizontal speed of the ball when the gun is aimed forward?
(b) Relative to the ground, what is the horizontal speed of the ball when the gun is aimed backward?
Definition
(a)37 m/s
(b)13 m/s
Term
An aircraft carrier is moving to the north at a constant 21 mph on a windless day. A plane requires a speed relative to the air of 145 mph to take off.
(a) How fast must the plane be traveling relative to the deck of the aircraft carrier to take off if the plane is headed north?
(b) How fast must the plane be traveling relative to the deck if the plane is headed south?
Definition
(a)124 mph
(b)166 mph
Term
Find the value that an observer would measure for the magnitude and direction of the free-fall acceleration in an elevator near the surface of the Earth if the elevator is accelerating downward at each of the following rates.
(a) 5 m/s2
Definition
5 m/s2 downward
Term
the laws of physics are the same in all intertial systems
Definition
first postulate of special reativitly
Term
The speed of light in a vacuum is costant regardless of the speed of the source or this speed of the obsever
Definition
2nd postulate of special relativity
Term
speed of light
Definition
300,000,000
Term
relativistic adjustment factor
Definition
1/√1-((v)(c)/c)^2
Term
relativistic Times
Definition
know speed of light X microseconds
Term
L/y
Definition
Term
yL
Definition
Term
What is the size of the adjustment factor for a speed of 0.5 c?
Definition
1.15
Term
pressure
Definition
force/area
Term
P=F/A
=6000N/2m^2
=3000N/m^2
Definition
Term
Kelvin
Definition
=C+273
Term
Ideal gas laws
Definition
PV=nRT
Term
Given that the carbon atom has a mass of 12 amu, how many carbon atoms are there in a diamond with a mass of 1 g?
Definition
5.02e22 atoms
Term
About how many atoms would it take to deposit a single layer on a surface with an area of 3 cm2? (Assume the atom has a cross sectional area of A = 1 10-20 m2.)
Definition
3e16 atoms
Term
You exert a force of 20 N on the head of a thumbtack. The head of the thumbtack has a radius of 4 mm. What is the pressure on your thumb?
Definition
3.94 atm
Term
density
Definition
mass/volume
Term
Solving For Volume
Definition
m/d
Term
Mass
Definition
v x D
Term
Archimedes' principle
Definition
the buoyant force is equal to weight of the weight of the displaced fluid
Term
An object has a mass of 290 kg and a volume of 0.4 m3.
What is its average density?

Will this object sink or float in water?
Definition
725 kg/m3

float
Term
A solid ball with a volume of 0.1 m3 is made of a material with a density of 3180 kg/m3. What is the mass of the ball?
Definition
318 kg
Term
What is the mass of a lead sinker with a volume of 9 cm3?
Definition
101.7 g
Term
if objects A and B are in thermal equilibrium with object C, then A and B are in thermal equilibrum with eachother
Definition
zeroth law thermodynamics
Term
the increase in the internal energy of a system is equal to the heat added plus the work done on the system
Definition
1st law of thermodynamics
Term
Absolute zero may be approached experimentally but can never be reached
Definition
3rd law of thermodynamics
Term
Thermal Expansion
Definition
ΔL=aLΔT
Term
ΔL=aLΔT
=(.000011/*C)(50m)(40*C)
=0.022m
Definition
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