✔ 最佳答案
Take the direction when the ball travels to the wall be positive.
Initial velocity, u = 17 ms-1
Final velocity, v = -10 ms-1
Time taken, t = 0.8 s
By impulse = change of momentum
Ft = mv – mu
F(0.8) = m(-10 - 17)
F = -33.75m N
And by Newton’s 2nd law of motion,
F = ma
We can obtain:
ma = -33.75m
a = -33.75 ms-2
So, the magnitude of average acceleration is 33.75 ms-2.
2007-09-23 09:23:28 補充:
It is because the time taken by the ball to rebound is 0.8 s. Therefore, the impact time (the time when the ball experience the force) is 0.8 s.