Ahiker wears a 7.5-kg backpack while climbing a mountain. after 30.0 min, the hiker is 8.2 m above the starting point. what is the average amount of power created by the hiker?

To travel at constant speed, a car engine provides 24kw of useful power. the driving force on the car is 600n. at what speed does it travel?

Asmall 12.00g plastic ball is suspended by a string in a uniform, horizontal electric field with a magnitude of 10^3 n/c. if the ball is in equilibrium when the string makes a 30 ° angle with the vertical, what is the net charge on the ball?

Asled is being held at rest on a slope that makes an angle θ with the horizontal. after the sled is released, it slidesa distance d1 down the slope and then covers the distance d2 alongthe horizontal terrain before stopping. find the coefficient ofkinetic friction μk between the sled and the ground, assumingthat it is constant throughout the trip. find the coefficient of kinetic frictionμk. express your answer in terms of someor all of the variables d1, d2, and θ.