Question

A 28-kg beginning roller skater is standing in front of a wall. By pushing against the wall, she is propelled backward with a velocity of -�1.2 m/s. While pushing, her hands are in contact with the wall for 0.80 s. Ignoring frictional effects, find the magnitude and direction of the impulse acting on the skater.

a) +34 N s

b) -34 N s

c) -42 N s

d) +42 N s

e) -53 N s

My teacher has marked -34 N s as the correct answer, but I think it should be -42 N s. Any ideas why? And if so, please explain as clearly as possible.

Answer 1

Impulse - 28kg -1.2m/s-0m/s ) -33.6Ns I -34Ns Hence the correct answer is option b) - 34Ns.