(II) A $1.60\text{-m-tall}$ person lifts a $1.65\text{-kg}$ book off the ground so it is $2.20\ \text{m}$ above the ground. What is the potential energy of the book relative to (c ) How is the work done by a person related to the answers in parts (a) and (b)

At room temperature, an oxygen molecule with mass $5.31 \times 10^{-26} \mathrm{~kg}$ has kinetic energy of about $6.25 \times 10^{-21}$ J. Determine the speed of the molecule.

(I) How long will it take a $1750\text{-W}$ motor to lift a $335\text{-kg}$ piano to a sizth-story window $18.0\ \text{m}$ above?

A hand exerts a constant horizontal force on a block that is free to slide on a frictionless surface (Fig. 7-36). The block starts from rest at point $\mathrm{A}$, and by the time it has traveled a distance $d$ to point $\mathrm{B}$ it is traveling with speed $v_B$. When the block has traveled another distance $d$ to point $\mathrm{C}$, what will its speed be? Explain your reasoning.

(II) An 85-g arrow is fired from a bow whose string exerts an average force of $105 \mathrm{~N}$ on the arrow over a distance of $75 \mathrm{~cm}$. What is the speed of the arrow as it leaves the bow?

An $85\mathrm{~g}$ arrow is fired from a bow whose string exerts an average force of $105 \mathrm{~N}$ on the arrow over a distance of $75 \mathrm{~cm}$. What is the speed of the arrow as it leaves the bow?

You have two springs that are identical except that spring 1 is stiffer than spring $2\left(k_{1}>k_{2}\right) .$ On which spring is more work done if they are stretched the same distance?

You have two springs that are identical except that spring 1 is stiffer than spring $2\left(k_1>k_2\right)$. On which spring is more work done: (a) if the two springs are compressed using the same force;

A baseball (m = 140 g) traveling 32 m/s moves a fielder's glove backward 25 cm when the ball is caught. What was the average force exerted by the ball on the glove?

(II) Two bullets are fired at the same time with the same kinetic energy. If one bullet has twice the mass of the other, which has the greater speed and by what factor? Which can do more work. and by what factor?

Explain the following seeming contradiction: You have two gases, A and B, in two separate containers of equal volume and at equal pressure and temperature. Therefore, you must have the same number of moles of each gas. Because the two temperatures are equal, the average kinetic energies of the two samples are equal. Therefore, since the energy of such a system corresponds to translational motion, the root mean square velocities of the two are equal, and thus the particles in each sample move, on average, with the same relative speed. Since A and B are different gases, each must have a different molar mass. If A has a higher molar mass than B, the particles of A must be hitting the sides of the container with more force. Thus the pressure in the container of gas A must be higher than that in the container with gas B. However, one of our initial assumptions was that the pressures were equal. Explain.

How much work must be done to stop a $925 \mathrm{~kg}$ car traveling at $95 \mathrm{~km} / \mathrm{h}$ ?

(II) Consider the track shown in Fig. 8-39.The section AB is one quadrant of a circle of radius $2.0\ \text{m}$ and is frictionless. B to C is a horizontal span $3.0\ \text{m}$ long with a coefficient of kinetic friction $\mu_k = 0.25$. The section CD under the spring is frictionless. A block of mass $1.0\ \text{kg}$ is released from rest A. After sliding on the track, it compresses the spring by $0.20\ \text{m}$. Determine: (c ) the velocity of the block at point C

(II) Consider the track shown in Fig. 8-39.The section AB is one quadrant of a circle of radius $2.0\ \text{m}$ and is frictionless. B to C is a horizontal span $3.0\ \text{m}$ long with a coefficient of kinetic friction $\mu_k = 0.25$. The section CD under the spring is frictionless. A block of mass $1.0\ \text{kg}$ is released from rest A. After sliding on the track, it compresses the spring by $0.20\ \text{m}$. Determine: (b) the thermal energy produced as the block slides from B to C