Topic 1 - Forces and Motion (GCSE Edexcel Combined Physics Retrieval Questions)

Define vector

A quantity that has both magnitude and direction

Define scalar

A quantity that has magnitude only

Name 3 scalar quantities.

distance, speed, mass, energy, temperature, power...

Name 3 vector quantities.

displacement, velocity, acceleration, force, momentum...

How can you draw a vector?

With an arrow, using a scale.

What is displacement?

The length and direction of the straight line from the initial position of an object to its position at a later time. Vector

What is distance?

The length of the path along which an object moves. scalar.

Give the equation linking speed, distance and time

Speed = distance/time

What is average speed?

The distance moved by an object divided by the time taken for this to happen. Scalar

Define instantaneous speed

The rate at which an object is moving at a given moment in time.

What's the difference between speed and velocity?

Speed is a scalar and velocity is a vector.

What is a typical walking speed in m/s?

1.5 m/s

What is a typical running speed in m/s?

5 m/s

What is a typical driving speed in m/s on the motorway?

30 m/s

What is the unit of velocity?

meters/second (m/s)

Describe a displacement-time graph for constant speed

Straight line sloping up and right

Describe a displacement-time graph for stationary object

Horizontal line

Describe a displacement-time graph for an accelerating object

Curved line

How do you find the velocity of a displacement-time graph?

Find the gradient of the line

Define acceleration

The rate of change in velocity

Give the equation linking acceleration, change in speed and time

Acceleration = change in speed/time taken

What is the unit of acceleration?

metres/second² (m/s²)

Give the equation linking final velocity, initial velocity, acceleration and displacement.

(final velocity)² = (initital velocity)² + 2 x acceleration x displacement

Describe velocity-time graph for constant speed

Horizontal line

Describe velocity-time graph for constant acceleration

Straight line sloping up and right

State how to find acceleration from velocity-time graph

Find the gradient of the line

State how to find distance from velicity-time graph

Find the area under the line

State how to find the acceleration from a speed-time graph that is curved

Draw a tangent to the curve and find the gradient of the line

Define weight

The affect of gravity on mass.

Define mass

The amount of matter in an object

What is the uniform acceleration of a falling object under gravity?

10 m/s²

What is the value of gravity on earth?

10N/kg

Give the equation linking weight, mass and gravitational field strength

Weight = mass x g

What is the unit for weight?

Newtons (N)

What is the unit for mass?

kilograms (kg)

What is air resistance?

The force exerted on an object by the air, when it moves through it.

State what happens to air resistance as an object speeds up

Air resistance increases

Define terminal velocity

Constant speed reached by a falling object when the drag force and weight are balanced

Why is gravity on the moon less than gravity on earth?

The moon has less mass than the earth.

What is force?

A push or pull upon an object resulting from the object's interaction with another object.

Describe the three things forces can do to a body

Change body's shape, speed or direction

What are contact forces?

A force that involves objects that are physically touching

Define a non-contact force

A force that involves areas of effect which are not physically touching

Define friction

Force that opposes motion

Define resultant force

Total force acting on a body

Define balanced force

Forces acting on a body are equal in size but opposite in direction

Define unbalanced force

The force acting in one direction is greater than the force acting in the opposite direction

What is a free-body diagram?

Diagrams used to show the relative magnitude and direction of all forces acting upon an object. The object is drawn as a small dot/square.

Why is air resistance not a non-contact force?

Because the object is physically touching air particles.

Name the three non-contact forces.

Gravitational, Magnetic, Electrostatic

What is newtons first law?

If the resultant force is 0 - the object remains stationary or is travelling at a constant speed

What is newtons third law?

For every action there is an equal sized force in the opposite direction

What is newtons second law?

F=ma

What is the unit for force?

Newtons (N)

Give the equation linking force, mass and acceleration?

F=ma

When the resultant force on an object is zero, what is happening?

The object is stationary or in constant motion.

When the resultant force on an object not zero, what is happening?

The object is accelerating or decelerating