Question

A car of mass 200kg, initially moving at 120km/h, slows to 60km/h in 40 seconds when hitting an object.

1) Calculate the momentum before hitting the object.
2) Calculate its momentum after hitting the object.
3) Calculate the change in momentum.
4) Calculate the resultant force once the car hits the object.

Answer 1

The momentum before hitting the object is 6660 kg*m/s, the momentum after hitting the object is 3340 kg*m/s, the change in momentum is -3320 kg*m/s, and the resultant force once the car hits the object is -83 N.

Step-by-step explanation:

1) To calculate the momentum before hitting the object, we can use the formula:

Momentum = mass x velocity

Given that the mass of the car is 200 kg and the initial velocity is 120 km/h, we need to convert the velocity to m/s:

120 km/h = 33.3 m/s

Therefore, the momentum before hitting the object is:

Momentum = 200 kg x 33.3 m/s = 6660 kg*m/s

2) To calculate the momentum after hitting the object, we can use the same formula:

Given that the final velocity is 60 km/h, we need to convert it to m/s:

60 km/h = 16.7 m/s

The momentum after hitting the object is:

Momentum = 200 kg x 16.7 m/s = 3340 kg*m/s

3) The change in momentum can be calculated by subtracting the initial momentum from the final momentum:

Change in momentum = Final momentum - Initial momentum

Change in momentum = 3340 kg*m/s - 6660 kg*m/s = -3320 kg*m/s

4) To calculate the resultant force once the car hits the object, we can use the formula:

Resultant force = Change in momentum / Time

Since the time is given as 40 seconds, we can substitute the values to calculate the resultant force:

Resultant force = -3320 kg*m/s / 40 s = -83 N