EQ's

Question 1

A horse is accelerating.

It has a driving force of 2000KN

Therefore, do the friction and air resistance forces acting on the horse add up to more or less than 2000KN

[1 mark]

Answer 1

Less than

Question 2

A horse is accelerating
The driving force acting on the horse is 2000KN. The friction and air resistance forces acting on it add up to less than 2000KN.

Is the horse accelerating or decelerating?
Explain your reasoning

[3 marks]

Answer 2

The horse is accelerating.
The driving force of 2000KN is greater than the forces of friction and air resistance.
Therefore the resusltant force is acting in a forward direction

Question 3

In a game of tennis, a ball is hit horizontally at a speed of 40 m/s.
After 0.5 seconds, its horizontal velocity has not changed, but it has
developed a downwards component of velocity of approximately 5 m/s.

By drawing a suitable scale diagram, determine the magnitude and
direction of the tennis ball after 0.5 seconds

say how you would do this question

Answer 3

1. draw scale diagram (triangle one to find magnitude of resultant force) using a suitable scale
2. find the angle between the resultant force and the horizontal line to find the direction. direction= x degrees horizontal

Question 4

A box is pushed over a rough surface at a constant velocity.

A frictional force of 4 N is acting on it.

Calculate the work which it does against friction when it is pushed through a distance of 50 cm

Answer 4

W=Fx s

W=?
F=4N
s=50cm - 50cm=0.5m

W= 4 x 0.5
W=2 Joules

Question 5

A car is moving with a velocity of 20 m/s.
The driver applies the brakes and the car comes to a stop

Describe the energy transfers in the car when the brakes are applied

[4 marks]

Answer 5

When the brakes are applied, a frictional force acts between the floor and the wheels

The kinetice energy store or the car is transferred to the thermal energy store of the brakes.
This causes the temperature of the breaks to increase.
The car slows down and the kinetic energy is dissipated into the surrounings

Question 6

Describe the
relationship between the force and the extension when the limit of proportionality has been exceeded

[2 marks]

Answer 6

The relationship is non-linear

as the extension is no longer directly proportional to the force applied

Question 7

Thom is carrying out an experiment to see the relationship between force and extension within the limit of proportionality.

He made a mistake when measuring the extension for each applied force.

Suggest a mistake he may have made.

[1 mark]

Answer 7

He measured the total length of the spring instead of its extension

Question 8

An object is at rotational equilibrium

The distance on he right side of the pivot is decreased

Suggest why the counterbalance on the left side of the pivot should be adjusted

[2 marks]

Answer 8

The clockwise moment being exerted is decreased

Unless the counterbalance is adjusted there will be a resultant force

So the object will topple over