A 1000 kg car strike a tree at 30 km/hr and comes to a stop in 0.15 s.
What is its initial momentum and average force on the car?
v(initial) = 30 km/hr = 30000 m / 3600 s
... v(final) = 0 m/s
... Δv = v(final) - v(initial)
... acceleration , (a), = Δv / t
initial momentum = mass * v(initial)
f = m a
To find the initial momentum of the car, you can use the equation:
Momentum = mass × velocity
Given:
Mass (m) = 1000 kg
Velocity (v) = 30 km/hr
First, we need to convert the velocity from km/hr to m/s since the unit of mass is in kilograms.
To do this, we use the following conversion factor:
1 km/hr = 1000 m/3600 s
So, 30 km/hr = (30 × 1000) / 3600 m/s = 8.33 m/s (rounded to two decimal places)
Now, we can calculate the initial momentum using the equation:
Momentum = mass × velocity
Momentum = 1000 kg × 8.33 m/s = 8330 kg m/s
Therefore, the initial momentum of the car is 8330 kg m/s.
To find the average force experienced by the car, we can use Newton's second law of motion:
Force = change in momentum / time
Given:
Change in momentum (Δp) = final momentum - initial momentum
Time (t) = 0.15 s
The final momentum is zero since the car comes to a stop. So, the change in momentum is equal to the initial momentum:
Δp = 8330 kg m/s - 0 kg m/s = 8330 kg m/s
Now, we can calculate the average force using the equation:
Force = change in momentum / time
Force = 8330 kg m/s / 0.15 s = 55,533.33 N (rounded to two decimal places)
Therefore, the average force on the car is 55,533.33 N.