Laws of Motion quiz

The inertia of a body depends on its:

The SI unit of impulse is:

Action and reaction forces:

The motion of a rocket is explained by:

Friction always opposes:

In general, compared with limiting static friction, kinetic friction is:

The apparent weight of a person in a freely falling lift is:

The coefficient of friction has:

On a banked road without friction, the centripetal force is provided by:

A body of mass 2 kg at rest is acted on by a force of 4 N for 3 s. Its final speed is:

Why do passengers fall forward when a bus stops suddenly? (2 marks)

Explain why it is easier to pull a lawn roller than to push it. (2 marks)

A body of mass 5 kg has an acceleration of 2 m/s^2. Find the force on it. (2 marks)

Find the limiting friction on a 10 kg block resting on a surface with coefficient of static friction 0.4. (2 marks)

What is rolling friction? Why is it smaller than sliding friction? (2 marks)

A 3 kg shell at rest explodes into two pieces of 1 kg and 2 kg. If the 1 kg piece moves at 6 m/s, find the velocity of the other piece. (2 marks)

State the conditions for the equilibrium of a particle under three concurrent forces. (2 marks)

Why does a horse have to pull harder at the start of motion than later? (2 marks)

Find the maximum speed of a car on a level circular road of radius 50 m if the coefficient of friction is 0.6. (2 marks)

Explain why a gun recoils when it is fired. (2 marks)

Two blocks of 3 kg and 5 kg lie in contact on a frictionless surface. A force of 16 N pushes the 5 kg block. Find the acceleration and the contact force between the blocks. (3 marks)

A 0.5 kg ball falls from 5 m and rebounds to 1.8 m. Find the impulse given by the floor. Take g = 10 m/s^2. (3 marks)

A constant force acting on a 3 kg body changes its speed from 2 m/s to 3.5 m/s in 25 s. Find the force. (3 marks)

A block slides down a 30 degree incline with a coefficient of kinetic friction of 0.4. Find its acceleration, taking cos 30 = 0.866. (3 marks)

A train of mass 2 x 10^5 kg accelerates at 0.5 m/s^2 against a resistive force of 10^4 N. Find the force exerted by the engine. (3 marks)

Read the passage and answer the questions. In a car crash test, a 70 kg dummy moving at 20 m/s is brought to rest. Without an airbag it stops in 0.1 s; with an airbag it stops in 1 s. (i) Find the change in momentum of the dummy. (ii) Find the average force without and with the airbag. (iii) Explain why the airbag is safer. (5 marks)

Read the passage and answer the questions. A 50 kg girl stands on a weighing machine in a lift. (i) Find the reading when the lift is at rest. (ii) Find the reading when it moves down with an acceleration of 1.8 m/s^2. (iii) Find the reading when it moves up with uniform speed. (5 marks)

Read the passage and answer the questions. A box rests on a plank. One end of the plank is slowly raised until the box just begins to slide at 30 degrees. (i) Find the coefficient of static friction. (ii) What is this angle called? (iii) What happens to the angle if the box is replaced by a heavier box of the same material? (5 marks)

Read the passage and answer the questions. A cyclist takes a circular turn of radius 20 m at 7 m/s on a level road. (i) What provides the centripetal force? (ii) Find the minimum coefficient of friction needed. (iii) Why does the cyclist lean inwards? (5 marks)

Read the passage and answer the questions. A rocket burns fuel and ejects hot gases backwards at high speed. (i) Which law explains the forward motion of the rocket? (ii) Does the rocket need air to push against? Explain. (iii) Why does the acceleration of the rocket increase as fuel burns? (5 marks)

Explain Newton's three laws of motion with examples from daily life. (6 marks)

State and prove the law of conservation of linear momentum using Newton's laws. Explain the recoil of a gun. (6 marks)

Explain static, limiting and kinetic friction. Draw a graph of friction against applied force and discuss methods of reducing friction. (6 marks)

Derive the maximum safe speed of a vehicle on a level circular road and explain why roads are banked. (6 marks)

Explain the method of solving problems in mechanics using free-body diagrams, with the example of two blocks connected by a string on a smooth table pulled by a force F. (6 marks)