So Confused PHYSICS HELP A car is traveling at 14 m/s .?

Question

A car is traveling at 14 m/s .

Part A) How fast would the car need to go to double its kinetic energy?

Part B) By what factor does the car's kinetic energy increase if its speed is doubled to 28 m/s ?

peterpan · Accepted Answer

A)
E1 = 1/2 m v1^2
E2 = 1/2 m v2^2
E2 / E1 = (v2 / v1)^2
(E2 / E1)^1/2 =  v2 / v1
v2 = v1 ( E2 / E1)^1/2 = v1 * 2^1/2 = 1.41 v1 = 19.8 m/s

B)
E2 / E1 = (v2 / v1)^2
E2 / E1 = 2^2 = 4
E2 = 4 E1

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