Question

A constant force is exerted on a cart that is initially at rest on an air track.  Friction between the cart and the track is negligible.  The force acts for a short time interval and gives the cart a certain final speed. To reach the same final speed with a force that is twice as much as the first mentioned force, the new force must be exerted on the cart for a time interval that is

A. half as long as the first time

B. four times as long as the first time

C. a quarter as long as the first time

D. twice as long as the first time

Answer 1

as we know

v = at

for constant velocity

a is inversely proportional to t

on increasing force to twice acceleration also gets doubled

hence

a2/a1 = t1/t2

t2 = 0.5 t1

option (a) is correct

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