After scoring the game winning goal, a hockey player celebrates by dragging the
ID: 1551479 • Letter: A
Question
After scoring the game winning goal, a hockey player celebrates by dragging the 55kg goal around the rink. The player drags the goal from rest to 7.0m/s uniformly over a period of 3.0s. (a) What is the force supplied by the player on the goal? (b) What is the amount of work done by the player on the goal in that 3.0s time? (c) What does impulse measure? (d) What is the impulse delivered to the goal by the player over the entire time t = 3.0s? (e) What is the instantaneous power due to the player at time t = 1.5s?Explanation / Answer
Given
mass m = 55 kg
final speed v = 7 m/s
t = 3 s
a)
let the accelration be a
v = u + a * t
Put value
7 = 0 + a * 3
a = 2.33 m/s^2
the force applied , F = m*a = 128.3 N
b)
the work done , W = kinetic energy gained
W = 0.5 * m * v^2 - 0 =
Put value = 0.5 * 55 * 7^2
W = 1347.5 J
c)
the impulse , I = change in momentum
I = m * v
Put value
= 385 kg.m/s
d)
the impulse delivered to the goal by the player is 385 kg.m/s