Question

An object of mass 10 kg is sliding on a frictionless horizontal surface with a uniform speed of 20 m/s. The force required to keep the object moving at the same speed along the same straight line is
1. 27 newtons
2. 24 newtons
3. 10 newtons
4. 0 newtons

Answer 1

Correct Answer - Option 4 : 0 newtons

The correct answer is 0 newtons.

CONCEPT:

• Newton's first law of motion: A body doesn't change its state 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 20 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.