Question

During an automobile crash test, the average force exerted by a solid wall on a 1,900 kg car that hits the wall is measured to be 150,000 N over a 0.30 s time interval. What was the initial speed of the car (in m/s) prior to the collision, assuming the car is at rest at the end of the time interval

Answer 1

Answer:

 u = 23.68 m/s

Explanation:

given,

mass of the car, m = 1900 Kg

Force exerted on the wall, F = 150,000 N

time of contact, t = 0.3 s

final speed of the car = 0 m/s

initial speed of the car = ?

we know,

Impulse is equal to change in momentum

J = m v- mu

J = 1900 x 0 - 1900 x (-u)

J = 1900 u

impulse is also equal to force into time

J = F x t

equating both equation of impulse

1900 u = F  x t

1900 u = 150000 x 0.3

1900 u = 45000

 u = 23.68 m/s

Speed of the car before collision is equal to 23.68 m/s