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A 25-kg child sits at the top of a 4-meter slide. After sliding down, the child is traveling at 5 m/s. How much PE does he start with? How much KE does he end with? How much energy is lost to friction?  


if you push a box across the floor  with a force of 30 N you push it 15 meters in 8 seconds how much work will you do  how much power did you use?

Respuesta :

scme1702
Potential energy = mgh
P.E = 25 x 9.81 x 4
P.E = 981 J

Kinetic energy = 1/2 mv²
K.E = 1/2 x 25 x 5²
K.E = 312.5 J

The difference in potential and kinetic energy is equal to the energy lost to friction.
Frictional loss = 981 - 312.5 = 668.5 J


Power = (force x distance) / time
Power = (30 x 15) / 8
Power = 56.25 Watts

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