A person doing a chin-up weighs 700 N, exclusive of the arms. During the first 25.0 cm of the lift, each arm exerts an upward force of 355 N on the torso. If the upward movement starts from rest, what is the person’s velocity at that point?

Un bibliotecario studente solleva un libro da $2,2$ kg dal pavimento ad un'altezza di $1,25$ m. Porta il libro per $8,0$ m verso gli scaffali e lo posiziona su uno scaffale che è $0,35$ m sopra il pavimento. Quanto lavoro compie sul libro?

A person doing a chin-up weighs $700 \mathrm{~N}$, exclusive of the arms. During the first $25.0 \mathrm{~cm}$ of the lift, each arm exerts an upward force of $355 \mathrm{~N}$ on the torso. If the upward movement starts from rest, what is the person's velocity at that point?

A certain rain cloud at an altitude of 1.75 km contains $3.20 \times 10 ^ { 7 }$ kg of water vapor. How long would it take for a 2.70-kW pump to raise the same amount of water from Earth’s surface to the cloud’s position?

A 7.00-kg bowling ball moves at 3.00 m/s. How fast must a 2.45-g Ping-Pong ball move so that the two balls have the same kinetic energy?

B. A 75 kg bobsled is pushed along a horizontal surface. Over 4.5 m., its speed goes from O to 6.0 m/s. Find the net force on the bobsled.

A mechanic pushes a $2.50 \times 10 ^ { 3 }$-kg car from rest to a speed of v, doing 5 000 J of work in the process. During this time, the car moves 25.0 m. Neglecting friction between car and road, find the horizontal force exerted on the car.

Tarzan swings on a 30.0-m-long vine initially inclined at an angle of $37.0 ^ { \circ }$ with the vertical. What is his speed at the bottom of the swing if he starts from rest?

A mechanic pushes a $2.50 \times 10 ^ { 3 }$-kg car from rest to a speed of v, doing 5 000 J of work in the process. During this time, the car moves 25.0 m. Neglecting friction between car and road, find v.

A 50-kg pole vaulter running at 10 m/s vaults over the bar. Her speed when she is above the bar is 1.0 m/s. Neglect air resistance, as well as any energy absorbed by the pole, and determine her altitude as she crosses the bar.

The masses of the javelin, discus, and shot are 0.80 kg, 2.0 kg, and 7.2 kg, respectively, and record throws in the corresponding track events are about 98 m, 74 m, and 23 m, respectively. Neglecting air resistance, calculate the minimum initial kinetic energies that would produce these throws.

A 650-kg elevator starts from rest and moves upward for 3.00 s with constant acceleration until it reaches its cruising speed, 1.75 m/s. What is the average power of the elevator motor during this period?

A block of mass $m$ on a horizontal frictionless tabletop is pushed against a horizontal spring, compressing it a distance $x$, and the block is then released. The spring propels the block along the tabletop, giving a speed $v$. The same spring is then used to propel a second block of mass $4 m$, giving it a speed $3 v$. What distance was the spring compressed in the second case? Express your answer in terms of $x$.

A block of mass 3.00 kg is placed against a horizontal spring of constant k=875 N/m and pushed so the spring compresses by 0.0700 m. If the block is now released and the surface is frictionless, calculate the block's speed after leaving the spring.