This question is driving me...?

Question

The maximum speed of a person on a swing is 5.0 m/s. The person's height above the ground is 0.75 m at the lowest point. How high above the ground is the person at the highest point? (energy conservation)


Please show your work. Thanks :)

Well other than that.... there is this picture describing how it looks, but no more additional info... would that help?

Answer 1

There is enough information to answer it. You don't need the mass. It can be eliminated from the equations by canceling.

Set the point of maximum speed to be the zero for potential energy.

Kinetic energy plus potential energy equals a constant:
T + U = constant
When the person is moving their maximum speed, they have zero potential energy (since we set our zero there). Their kinetic energy at this point is:
T = 1/2*m*v^2
T = 1/2*m*5^2
T = 12.5*m (not bothering to write units)

At the top of their swing, their velocity drops to zero, so all of their kinetic energy has become potential energy:
U = m*g*h
12.5*m = m*g*h
12.5 = g*h
12.5 = 9.81*h
h = 1.27 meters above the zero point

However, the zero point is 0.75 meters, so their height above the ground at their highest point is
1.27 + 0.75 = 2.02 meters

Answer 2

DON'T LISTEN TO THE FOOLS WHO SAID THERE ISN'T ENOUGH INFO TO SOLVE!

Conservation of energy!

The maximum sped of the person on the swing will occur at the lowest point.

At the top the highest point v=0 so KE=0 and the energy is all potential.

Ei=Ef
KEi+PEi=PEf
.5mv^2+mgh=mgH
m cancels out
.5v^2+gh=gH
.5(25)+9.8(.75)=9.8H


CORRECT ANSWER H=2.03 m

Answer 3

I concur

If this is truly all the information you have, then I sympathise with you because I now remember how stupid textbook physics problems are.

Answer 4

not enough information given to accurately answer this question

Answer 5

need the weight of the guy

Answer 6

yea you need more information to answer that question.