Question

An object of mass 10kg is sliding on a frictionless horizontal surface with a uniform speed of 9 m/s. The force required to keep the object moving at the same speed along the same straight line is
1. 60 newtons
2. 54 newtons
3. 0 newtons
4. 36 newtons

Answer 1

Correct Answer - Option 3 : 0 newtons

The correct answer is 0 newtons.

CONCEPT:

• Newton's first law of motion: A body doesn't change its states until an external force acts on it.
• The force is the product of mass and Acceleration

Force = Mass × Acceleration

CALCULATION:

• The body is moving with a constant velocity of 9 m/s, So acceleration in the body is zero.

                             Force = Mass × Acceleration

                             Force = 10 Kg × 0

                             Force = 0 N

Mistake Point:

• Do not apply friction law as the given surface is frictionless.
• Friction law is not applicable in this case.