Question

For an object is moving with constant positive acceleration, which of the following statements is true? [Enter all correct answers eg. B or AC or ABC or ...]

A) The position of the object must also be positive

B) The velocity of the object must also be positive

C) The velocity of the object must be zero

D) The velocity of the object must be continually changing by the same amount each second

E) None of the above

Please explain.

Answer 1

acceleration,a = dv/dt ; where v = velocity and t = time

since acceleration = positive constant

therefore, dv/dt = positive constant(k)

or, v = kt

thus, velocity increases at a constant rate

now, (final velocity)² - (initial velocity)² = 2*acceleration*displacement

now, final velocity>initial velocity

so, L.H.S of the equation is positive

THus, R.H.S must also be positive

so, displacement is also positive and hence the position is positive

Answer 2

the correct option are :-

A) The position of the object must also be positive

B) The velocity of the object must also be positive

D) The velocity of the object must be continually changing by the same amount each second