Impulse Formula

An impulse is a force applied for a specified period of time. Thus I, the impulse, is equal to a force, F, x time, t.

I = Ft

I = impulse, N-sec

F = force, N

t = time, sec

Impulse Formula Questions:

1) You swat at a fly, hitting the lampshade with a force of 100 Newtons, for 100 milliseconds. What is the impulse energy?

Answer: The force, F = 100 N and time, t = 100 millisec = 0.1 sec.

I = Ft

I = 100 N x 0.1 sec

I = 10 N-sec

2) You tap a ball with a force of 50 N and the total Impulse is 11 N-sec. How long did it take you?

Answer: The force, F = 50N, and the Impulse, I = 11 N-sec.

I = Ft

I/F = t

11 N-sec/ 50 N = t

t = 0.02 sec = 20 x 10^-3sec = 20 millisec