Author Question: Bumpers on cars are not of much use in a collision. To see why, calculate the average force a bumper ... (Read 80 times)

mydiamond · **on:** Jul 29, 2018

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) 3.2 104 N
B) 1.6 104 N
C) 5.4 104 N
D) 1.8 104 N
E) 6.5 105 N

Question 2

A weightless spring of force constant 2.50 N/cm is 15.0 cm long when nothing is attached to it. It is now used to pull horizontally on a 12.5 kg box on a smooth horizontal floor.

You observe that the box starts from rest and moves 96.0 cm during the first 1.60 s of its motion. How long is the spring during this motion?