Question

Momentum problme

Answer 1

This uses F = d(mv)/dt another form of Newton's F = ma.
mv is momentum, where m is mass in kg and v is velocity in m/s.
time = momentum change / force. Off you go.

Answer 2

a) W = mg
15680 = m *9.81
m = 15680/9.81
m = 1598.37kg

Therefore the car weighs 1598.37 kilograms

b) P = mv
P = 1598.37 * 20
P = 31967.38 Ns

Therefore the initial momentum is 31967.38 Ns

c) The change is momentum is -31967.38 Ns because the momentum is lost

d) Impulse = Change in momentum
Therefore Ft = -31967.38
-6.40*10^2 t = -31967.38
t = -31967.38/(-6.40*100)
t = 49.95 seconds

Therefore the braking lasts for approximately 49.95 seconds.