If an object is in equilibrium, which of the following statements is not true?

Explanation
An object is said to be in equilibrium if net force in every direction acting on the object is zero .

According to newton second law.

Net force = m*a

Now because mass of an object can not be zero

So acceleration of an object is zero

Option a) is incorrect because if speed is constant and not changing with time then change in speed is zero.

So acceleration which is rate of change of volocity is zero .

Option b is incorrect because

Acceleration is zero so object is in equilibrium.

Option c is incorrect because net force acting on the object is zero so object is in equilibrium

Option d is correct because

It is not necessary for an object to be in rest to be in equilibrium. As discussed in option a ) moving with constant velocity can also cause equilibrium.

Option e is incorrect because

If volocity is constant then change in velocity is zero .

So acceleration is zero

Hence object is at equilibrium

Answer
Option (d) is correct answer.