Answer:
t = 0, p = 12.0, v = 6.00
t = 20, p = 112, v = 56.0
t = 25, p = 62.0, v = 31.0
Explanation:
Impulse = change in momentum
J = Δp
FΔt = mΔv
The impulse equals the area under the F vs t graph.
At t = 0 s, the initial velocity is 6.00 m/s, so the momentum is:
p = (2.00 kg) (6.00 m/s)
p = 12.0 kg m/s
From t=0 s to t=20 s, the impulse is:
J = (20 N) (5 s) + ½ (20 N) (5 s) + ½ (-10 N) (10 s)
J = 100 Ns
So the new momentum is:
p = 12.0 kg m/s + 100 kg m/s
p = 112 kg m/s
And the new velocity is:
v = (112 kg m/s) / (2.00 kg)
v = 56.0 m/s
From t=20 s to t=25 s, the impulse is:
J = (-10 N) (5 s)
J = -50 Ns
So the new momentum is:
p = 112 kg m/s − 50 kg m/s
p = 62.0 kg m/s
And the new velocity is:
v = (62.0 kg m/s) / (2.00 kg)
v = 31.0 m/s
