Newton's Laws | MCQs

Explanation

Newton's first law of motion is also called as Law of inertia.

• Inertia is the ability of a body by virtue of which it opposes a change.
  
• According to Newton’s first law of motion, an object will remain at rest or in uniform motion in a straight line
• unless acted upon by an external force.
  • The inertia of rest: When a body is in rest, it will remain at rest until we apply an external force to move it. This property is called inertia of rest.
  • The inertia of motion: When a body is in a uniform motion, it will remain in motion until we apply an external force to stop it. This property is called inertia of motion.

Explanation

To find the acceleration of the sledge, we can use Newton's second law of motion: F = ma, where F is the net force acting on the sledge, m is its mass, and a is its acceleration.

First, we need to find the net force acting on the sledge. The force applied by the man is 60 N, and the force of friction is 20 N, so the net force is:

F = 60 N - 20 N = 40 N

Next, we can plug in the values to Newton's second law:

40 N = (25 kg) × a

To find the acceleration, we can divide both sides by the mass:

a = 40 N / 25 kg = 1.6 ms^-2

Therefore, the acceleration of the sledge is 1.6 ms^-2.

Explanation

This is a statement of Newton's second law of motion, which states that the force (F) required to accelerate an object is proportional to its mass (m).