Question
A. How much impulse is needed to stop a 1,500 kg car that travels at 10.0 m/s?
B. How much force of friction is needed to stop the car in 5.0 s? What coefficient of friction is needed to stop the car in this time?
B. How much force of friction is needed to stop the car in 5.0 s? What coefficient of friction is needed to stop the car in this time?
Answers
Anonymous
Impulse = force * time = change in momentum
= 1500 * 10
B. Two ways
1. impulse = force* time = 15000
so force = 15000/5 = 3,000 Newtons
2. stop distance = average speed * time = 5*5 =25 meters
force * 25 meters = initial kinetic energy
25 F = (1/2) 1,500 * 100
F = 3,000 Newtons again
Now mu
mu m g = F
mu = 3,000 / [ 1500*9.81 ]
= 1500 * 10
B. Two ways
1. impulse = force* time = 15000
so force = 15000/5 = 3,000 Newtons
2. stop distance = average speed * time = 5*5 =25 meters
force * 25 meters = initial kinetic energy
25 F = (1/2) 1,500 * 100
F = 3,000 Newtons again
Now mu
mu m g = F
mu = 3,000 / [ 1500*9.81 ]