Third Law of Motion

Q. An object of mass 1 kg travelling in a straight line with a velocity of 10 m/s collides with, and sticks to, a stationary block of mass 5 kg. Then they both move off together in the same straight line.
a) Calculate the total momentum just before the impact and just after the impact.
b) Calculate the velocity of the combined object.

\( \stackrel{5}{\longrightarrow} \quad 5 kg \)
[3 Marks]
[NCERT]
[Conservation of Momentum]

Q. Newton’s third law of motion states that for every action, there is an equal and opposite reaction. Which of the following statements can be inferred from the above-mentioned law of motion?
Statement 1: For every interaction, there is a pair of forces acting on the two interacting objects.
Statement 2: The magnitude of the force on the first object equals the magnitude of the force on the second object.
Statement 3: Forces always come in pairs - equal and opposite action-reaction force pairs.
Statement 4: Action and its reaction act on the same bodies.
Statement 5: Action and its reaction act on two different bodies.

1. All statements can be inferred from $3^{rd}$ law of motion
2. All statements except 5 can be inferred from $3^{rd}$ law of motion
3. All statements except 4 can be inferred from $3^{rd}$ law of motion
4. Only statement 1 can be inferred from $3^{rd}$ law of motion

Q.

Among these two scenarios, identify the action force and reaction force.

Scenario 1$:$ A person is pushing a book on the table.

Scenario 2$:$ A gun is fired

Then match the following.

$$\begin{array}{cc}coloumn-A& coloumn-B\\ 1.Actionforce& a)forceappliedbythebookontheboy\\ 2.Reactionforce& b)forceappliedbytheboyonthebook\\ & c)recoilforceonthegun\\ & d)acceleratingforceonthebullet\end{array}$$

1. 1-b and 2-a, c and d

2. 1-b and d, 2-a and C

3. 1-a and c , 2-b and d

4. 1-a and 2-b, c and d

Q. The action and the reaction forces act on two different bodies.

1. False
2. True

Q. A boy hits a football with some amount of action force. What can be inferred from this scenario?

1. The action and reaction forces differ in magnitude.
2. The reaction force acts on the boy's foot.
3. The action and reaction forces act only on the boy's foot.
4. There won't be any reaction force.

Q.

A body is kept on a table. The object is pushed downwards with a force equal to its weight. But the table exerts an equal and opposite force on the object, hence keeping it at rest.

1. True

2. False

Q.

Action and reaction are pair of forces which acts on __ body(s).

Q.

The radially inward force towards the centre that deflects a particle from its straight line path:

1. Electrostatic force
2. Centrifugal Force
3. Gravitational force
4. Centripetal force

Q.

________ force is the apparent outward pseudo-force that draws a rotating body away from its centre of motion.

1. Electrostatic force
2. Centrifugal force
3. Nuclear force
4. Centripetal force

Q.

Action and reaction are equal and opposite and act on:

1. None of these
2. Same body
3. Different bodies
4. Same or different