Yes, four times is correct.
Kinetic energy is calculated according to the formula:
KE = (1/2)mv²
So if v2/v1=90/45=2
KE2/KE1
= (1/2)mv2²/((1/2)mv1²)
= (v2/v1)²
= 4
What is the change in kinetic energy of a baseball thrown at 90 mph compared to one thrown at 45 mph?
it is four times as much right?
3 answers
In fact, the "change" is
KE2-KE1
=(1/2)m(v2²-v1²)
=(1/2)m((2*v1)²-v1²)
=3*(1/2)mv1²
I.e. the "change" in KE is three times that of the slower ball.
In fact, I would use the word "difference" and not "change", since the balls are distinct.
KE2-KE1
=(1/2)m(v2²-v1²)
=(1/2)m((2*v1)²-v1²)
=3*(1/2)mv1²
I.e. the "change" in KE is three times that of the slower ball.
In fact, I would use the word "difference" and not "change", since the balls are distinct.
ok, thanks for your help
2 answers