How long is the glider in contact with the spring?

A 500 g air-track glider collides with a spring at one end of the track. The figure (Intro 1 figure) shows the glider’s velocity and the force exerted on the glider by the spring. (Intro 2 figure)

F=m(v-u)/t
v=3 , u=-3 from fig 1
maximum force = 36N
36=0.5(6)/t
t=3/36
=1/12=0.08sec

F * t = change in momentum. You can read the change in momentum from the velocity graph, since you know m.

Doing F * t is a little trickier though because F is not constant. The impulse is the area under that triangle, which is (1/2) * base * height. The base is delta-t (your unknown) and the height you can read from the graph.

Set that area equal to the change in momentum. Solve for delta-t.

impulse=0.5(36N)t because that’s the area below the triangle
p=mv
0.5(36N)t=(0.5kg)(3- -3)
t=.167 s
if you don’t divide the impulse by two like in the first answer, then you’ll get it wrong

Leave a Comment