Question

Car A has a mass of 1,000 kg and is traveling 60 km/hr. Car B has a mass of 2,000 kg and is traveling 30 km/hr. Which

statement best compares the kinetic energy of Car A with that of Car B?
** A The kinetic energy is equal between the two cars.
** B The kinetic energy of Car A is half as much as Car B.
** C The kinetic energy of Car A is twice as much as Car B.
** D The kinetic energy of Car A is four times as much as Car B.

Answer 1

C

Step-by-step explanation:

First we change the unit of velocity to SI unit for the sake of consistency

1. so velocity of car A, v1=
2. 
   `(60 * 1000)/(1 * 3600) = 16.66...m {s}^( - 1)`
3. velocity of Car B, v2=
4. 
   `(30 * 1000)/(1 * 3600 ) = 8.333...m {s}^(- 1)`

KE for car A, KE1=1/2 mv^2

so , KE1= 0.5 x 1000 x (16.67)^2 = 138,944.45

KE for Car B, KE2=1/2 mv^2

so, KE2= 0.5 x 2000 x (8.334)^2 = 69,455.556

So KE1 is approximately equal to two times of KE2

So the answer is C