A particle of mass 0.40kg moving initially with a constant speed of 10ms^-1 to the north is subject to a constant force of 8.0N
A particle of mass 0.40kg moving initially with a constant speed of 10ms-1 to the north is subject to a constant force of 8.0N directed towards the south for 30s. Take the instant the force is applied to be t = 0, the position of the particle at that time to be x = 0, and predict its position at t = - 5s, 25s, 100s.
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a = - 20ms-2 0 ≤ t ≤ 30s
t = - 5s:
x = ut = -10 × 5 = - 50m
t = 25s :
x = ut + (½) at2 = (10 × 25 - 10 × 625)m = - 6km
t = 100s :
First consider motion up to 30s
x1 = 10 × 30 -10 × 900 = - 8700m
At t = 30s, v = 10 - 20 × 30 = - 590ms-1
For motion from 30s to 100s :
x2 = 590 × 70 = - 41300m x = x1 + x2 = - 50km
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