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The physicists are known to be daredevils. One of them, a physics professor’s gravitational potential energy is 1400 J as she sits 2 m above the ground in a sky diving airplane before it takes off.  What is the same professor’s gravitational potential energy when she begins to jump from the airplane at an altitude of 955 m? 

A physics student shoves a 0.70-kg block from the bottom of a frictionless 30.0° inclined plane. The student performs 5.0 J of work and the block slides a distance s along the incline before it stops. Determine the value of s.

A spinning star begins to collapse under its own gravitational pull.  Which one of the following occurs as the star becomes smaller?

A 0.085-kg ball moving to the right with a speed of 15 m/s is struck by a racket, causing it to move to the left with a speed of 15 m/s.  If the ball remains in contact with the racquet for 0.025 s, what is the magnitude of the average force exerted on the ball?

The physicists are known to be daredevils. One of them, a physics professor’s gravitational potential energy is 1300 J as she sits 2 m above the ground in a sky diving airplane before it takes off.  What is the same professor’s gravitational potential energy when she begins to jump from the airplane at an altitude of 915 m? 

A planet completes one rotation about the axis passing through its poles in 7.5 × 104 s.  Given this information, what is the angular speed of the planet about its axis?

A ball of mass M moves in a circular path on a horizontal, frictionless surface. It is attached to a light string that passes through a hole in the center of the table. If the string is pulled down, thereby reducing the radius of the path of the ball, the speed of the ball is observed to increase. Complete the following sentence: This occurs because

A spinning disc rotating at 130 rev/min slows and stops 31 s later.  How many revolutions did the disc make during this time?

How much power is needed to lift a 55-kg student vertically upward at a constant speed of 0.44 m/s?

A 75-kg skater begins a spin with an angular speed of 2.0 rad/s. By changing the position of his arms, the skater decreases his moment of inertia to one-fifth of its initial value. What is the skater’s final angular speed?