Question

I NEED HELP BADLY


While driving her car at 40 m/s, Andrea (with a mass of 50-kg) stops short to avoid hitting a squirrel crossing the road. If the seat belt is in contact with Andrea for 0.5 seconds, determine:

a.) Andrea’s initial momentum





b.) Andrea’s final momentum





c.) What is the change in momentum (impulse)?





d.) What is the force that the seatbelt exerts on Andrea?
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Answer 1

Answer:

a) Andrea's initial momentum, 200 kg m/s

b) Andrea's final momentum, 0

c) Impulse,  = - 200 Ns

d) The force that the seat belt exerts on Andrea, - 400 N

Explanation:

Given data,

The initial velocity of the car is, u = 40 m/s

The mass of Andrea, m = 50 kg

The time period of deceleration, a = 0.5 s

The final velocity of the car, v = 0

a) Andrea's initial momentum,

               p = mu

                  = 50 x 40

                  = 200 kg m/s

b) Andrea's final momentum

                  P = mv

                     = 50 x 0

                    = 0 kg m/s

c) Impulse

                   I = mv - mu

                     = 0 - 200

                    = - 200 Ns

The negative sign indicated that the momentum is decreased.

d) The force that the seat belt exerts on Andrea

                   F = (mv - mu)t

                     = (0 - 200) / 0.5

                     = - 400 Ns

Hence,the force that the seat belt exerts on Andrea is, - 400 N