15)Bumpers on cars are not of much use in a collision.To see why,calculate the average force a bumper would have to exert if it brought a 1200-kg car (a so-called compact model)to a rest in 15 cm when the car had an initial speed of 2.0 m/s (about 4.5 mph).(Bumpers are built with springs that compress to provide a stopping force without,hopefully,denting the metal.) A) 1.8 × 10⁴ N B) 1.6 × 10⁴ N C) 5.4 × 10⁴ N D) 6.5 × 10⁵ N E) 3.2 × 10⁴ N

Question

Quizplus · Accepted Answer

We can use the formula for average force:

F = (mv^2)/(2d)

where m is the mass of the car, v is the initial velocity, and d is the distance over which the bumper compresses.

Plugging in the given values, we get:

F = (1200 kg x (2.0 m/s)^2) / (2 x 0.15 m)

F = 16000 N

This corresponds to choice B, 1.6 x 10^4 N.

15)Bumpers on Cars Are Not of Much Use in a Collision.To