A small car and a heavy pickup truck are both out of gas. The truck has twice th
ID: 1285271 • Letter: A
Question
A small car and a heavy pickup truck are both out of gas. The truck has twice the mass of the car. After you push the car and the truck for the same distance with the same force, what can you say about the momentum and kinetic energy of the car and the truck? Ignore friction.
The answer is "They have the same kinetic energy, but the truck has more momentum than the car." Why is this the right answer? Please explain without equations because the only detailed explanation I found was only using equations and honestly I would rather get a simple, yet effective explanation.
Explanation / Answer
f=ma
acceleration of truck,at = f/mt (f is same in both cases, mt=2mc)
acceleration of car , ac = f/mc
v2-u2=2as (u=0 , s is same in both cases)
vt=sqrt(2ats)
vc =sqrt(2acs)
momentum of truck = mt*vt = 2mc*vc/sqrt(2) = sqrt(2)*mc*vc
mometum of car = mc*vc
momentum of truck is greater than mometum of car
kinetic energy of truck = 1/2 *mt*vt2= 1/2 mc*vc2
kinetic energy of car = 1/2 mc*vc2
kinetic energy of truck = kinetic energy of car