Question

Newton’s first law states that if an objects velocity is changing a _____ must be acting on it.

a) force
b) mass
c) acceleration
d) inertia

Answer 1

(a)

Explanation

• Newtons First Law can be written as the formula

`f = ma`

since acceleration is the changing of velocity as its formula is

`(v2 - v1)/(t)`

Thus, a force must be acting on an accelerating/decelerating object

• It is not mass as the mass does not act on the object but rather the mass is acting on the surface of the ground.

• Changing velocity is already acceleration

• inertia is the term used to describe Newtons first law