Solve the problem.
-The kinetic energy K of a mass is proportional to the square of its velocity v. If K = 4320 joules when v = 12 m/sec, what is K when v = 8 m/sec?
A) 1280 joules
B) 2560 joules
C) 1920 joules
D) 2240 joules

Question

Quizplus · Accepted Answer

We know that K is proportional to v^2, so we can write:
K = k*v^2
where k is a constant of proportionality. 
To find k, we use the given information that K = 4320 joules when v = 12 m/sec:
4320 = k*(12^2)
Solving for k, we get k = 30.
Now we can use this value of k to find K when v = 8 m/sec:
K = 30*(8^2) = 1920 joules.
Therefore, the correct answer is C.

Solve the Problem. -The Kinetic Energy K of a Mass Is Proportional to Is