1. What is force?

Force is the pull or push that is applied to an object to make it move or stop or to change its direction, speed, or shape.It can be calculated using the formula F = m × a, where F is force, m is mass, and a is acceleration. The unit of force is Newton (N).

Example- Pushing or pulling a door, drawer or kicking a football to move it are examples of force.

4. What are unbalanced forces?

If the resultant of applied forces is greater than zero, they are called unbalanced forces which can move a stationary object, increase or decrease the speed of a moving object, stop a moving object, and change the shape and size of an object.

6. Who studied the ideas of Galileo and gave the three laws of motion?

Newton studied the ideas of Galileo and gave the three laws of motion  (i) Newton's First Law of Motion (Law of Inertia), (ii) Newton's Second Law of Motion, and (iii) Newton's Third Law of Motion.

7. What is Newton's First Law of Motion and can you give an example of it in everyday life?

Newton's First Law of Motion states that an object will remain at rest or in uniform motion in a straight line unless acted upon by an external force. For example, when a person is standing inside a bus and the bus suddenly moves, the person falls backwards due to inertia.

10. What is Newton's Third Law of Motion, and give an example?

Newton's Third Law of Motion states that every action has an equal and opposite reaction. For example, when a gun is fired, the gun recoils backward due to the reaction of the bullet moving forward.

12. A cricket ball of mass 150 grams is thrown at a speed of 120 km/h. What is the momentum of the ball?

Here, the mass (m) of the ball is 150 grams or 0.15 kg, and the velocity (v) is 120 km/h or 33.33 m/s.

Using the formula: p = m x v, we get:

p = 0.15 x 33.33 = 5 kg m/s