# Shared Flashcard Set

## Details

Forces
Force basics
23
Physics
Not Applicable
08/24/2005

Term
 What is a force?
Definition
 A push or a pull
Term
 What effect does a force have?
Definition
 It makes an object change speed or direction - in otherwords accelerate!OR it could make an object rotate OR be deformed.
Term
 What are forces measure in?
Definition
 newton (N) - must be a capital letter!
Term
 Is a force a scalar or vector quantity?
Definition
 It is a vector - that is because the direction the force acts in makes a big difference. With scalars there is no directional element involved.
Term
 How is a force represented on a diagram?
Definition
 By an arrow. The length of the arrow represents the SIZE of the force (sometimes called the magnitude of the force).The direction of the force is given by the orientation of the line and the arrow head.You should put a scale on your diagram. For example: 1cm represents 10N
Term
 What is the term for a force that is pushing in the same direction as an object is already travelling in?
Definition
 A driving force.
Term
 What is the term for a force that is pushing in the opposite direction as that an object is already travelling in?
Definition
 A counter force
Term
 If a driving force is applied to an object what does it make that object do?
Definition
 Accelerate.
Term
 If a counter force is applied to an object what does it make that object do?
Definition
 Decelerate
Term
 What is a 'net force'?
Definition
 The single force that could replace a group of more than one forces acting on an object. For example: if you have 10N pushing up on an object and 6N pushing down that is the same as having one force of 4N pushing up - so 4N up is the net force acting on the object.
Term
 If there is no net force acting on an object what will it do?
Definition
 It will not accelerate - it will keep on going at the same speed (which might be 0m/s!!) and in the same direction as it was doing before the system of forces that resulted in 'no net force' acted on it.
Term
 Sketch a diagram to show a 1N force to the left and a 3N force to the right. Then sketch a diagram to show the net force acting.
Definition
 [image]
Term
 Sketch a diagram to show a 2N force to the left and a 2N force to the right. Then sketch a diagram to show the net force acting.
Definition
 [image]
Term
 What is the equation that relates the size of the net force acting on an object to the acceleration is produces?
Definition
 F = ma where:F = force in newtons (N) m = mass in kilograms (kg)a = acceleration in metres per second squared (m/s2)
Term
 What is the acceleration due to gravity?
Definition
 The acceleration produced on all masses when they are near the Earth's surface is called the acceleration due to gravity. This is the same whatever the mass of the object! It is about 10m/s2.
Term
 When you fall from an aeroplane what force makes you accelerate downwards?
Definition
 Gravity.
Term
 When you parachute from an aeroplane what counter force acts on you?
Definition
 Drag or air resistance - the faster you go the bigger the air resistance force will be.
Term
 When you are in contact with a surface as you move what counter-force acts on you?
Definition
 Friction - the faster you go the bigger the frictional force will be and the bigger the area of you in contact with the surface the bigger the frictional force will be.
Term
 When you open a parachute what force increases?
Definition
 Air resistance increases - so you slow down.
Term
 What is Newton's first Law?
Definition
 Newton's First Law, says that if the forces on an object are in balance, the object's speed and direction of motion won't change. - Newton's First Law states that an object will remain at rest or in uniform motion in a straight line unless acted upon by an external force.
Term
 What is Newton's Second Law?
Definition
 At a simple level it is that F=mawhere:F = force in newtons (N) m = mass in kilograms (kg)a = acceleration in metres per second squared (m/s2)A better definintion of it is that the rate of change in momentum of a body is the same as the force applied to it - but you won't come across momentum until GCSE.
Term
 What is Newton's Third Law?
Definition
 Newton's Third Law, says that every action has an equal and opposite reaction.This means that when you push or pull something, it pushes or pulls back at you. Forces are two-way affairs, they're about the way that objects affect each other.Newton's third law is one of the fundamental symmetry principles of the universe. Since we have no examples of it being violated in nature, it is a useful tool for analyzing situations with are somewhat counter-intuitive. For example, when a small truck collides head-on with a large truck, your intuition might tell you that the force on the small truck is larger. Not so! They both exert equal forces on each other.... but as the mass of the big truck is greater the change in its speed (what gives you a jolt if travelling in it!) is smaller so you feel less effect and THINK the force is smaller![image]
Term
 Which of Newton's Laws gets called the 'Law of Intertia'?
Definition
 The First Law.
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