1- In raising a 4600 N piano with a pulley system, the workers note that for every 2 m of rope pulled down, the piano rises 0.2 m. Ideally, how much force is required to lift the piano?
2-Suppose an automobile has 1300 J of kinetic energy. When it moves at twice the speed, what will be its kinetic energy?
2007-02-18 12:41:07 · 3 answers · asked by Jane A 3 in Science & Mathematics ➔ Physics
Pulley system supplies 10:1 reduction, so force required is 460N.
Kinetic energy is ½mv², so doubling the velocity (speed) multiplies the kinetic energy by a factor of 4 (2²). Kinetic energy would be 5200 J.
2007-02-18 13:22:12 · answer #1 · answered by CheeseHead 2 · 0⤊ 0⤋
460 N. You have a 10:1 ratio
2600 J. m*v=1300 2*m*v=2600.
2007-02-18 20:46:51 · answer #2 · answered by Walking Man 6 · 0⤊ 0⤋
ratio 10-1
4600/10
=460N
1300=.5mv^2
x=.5m(2v)^2
x=2v^2
1300=.5v^2
(ms cancel)
v=50.99
put it into other equation to get x=5200J
2007-02-18 22:43:31 · answer #3 · answered by climberguy12 7 · 0⤊ 0⤋