Question

Which of the following forces can change velocity?

Answer 1

Answer:

Option A and Option D are correct.

Explanation:

We have the Newton's second law, that is rate of change of momentum is force.

      $\frac{dP}{dt}=F\\\\\frac{mv-mu}{dt}=F$

So if there is a force  mv - mu ≠ 0

                                 v - u ≠ 0

                                 v ≠ u

                     Final velocity ≠ Initial velocity.

  a) Option A is correct since there is a force

  b) Option B is wrong since total force is zero.

  c) Option C is wrong since total force is zero.

  d) Option D is correct since there is an effective force

Option A and Option D are correct.          

Answer 2

Unequal opposite forces.
(They're unbalanced.)