Twenty students ride a school bus that has a mass of 2500 kg and moves with a speed of 4.25 m/s. the driver has a mass of 75.0 kg. (a) What is the magnitude of the momentum of the bus and its passengers if the average mass of each student is 125 kg? (b) If eight students get off from the bus, what must be the speed of the bus to maintain its original momentum? please heelpp im begging youu...T^T

The new velocity would have to be 5.29 m/s.

Explanation:

2500 kg (bus) + 75 kg (driver) + 2500 kg (students) = 5075 kg

Substituting into the formula:  

P = 4.25 m/s  x  5075 kg

P= 21,568.75 kg m/s

As I mentioned, since there are two factors that determine momentum, we can still have the same momentum if we change the numbers around.  If we subtract eight of the twenty students, the mass would change by 1000 kg.

8 x 125 kg = 1000 kg

Subtract 1000 kg from the initial mass, 5075 kg, and you get 4075 kg.

To maintain the same number on momentum, we would have to increase the number for velocity.  We could find that value by doing the following:

21,568.75 kg m/s  =  (v) (4075 kg)

Divide both sides by 4075 kg, and we discover what the new velocity would have to be:

21,568 kg m/s /4075 kg  =  (v) (4075 kg) /4075 kg

5.29 m/s  =  (v)