On the moon, the acceleration due to the effect of gravity is only about $1 / 6$ of that on Earth. An astronaut whose weight on Earth is $600 \mathrm{~N}$ travels to the lunar surface. His mass, as measured on the moon, will be $(a) 600 \mathrm{~kg}$, (b) $100 \mathrm{~kg}$, $(c) 61.2 \mathrm{~kg}$, $(d) 9.81 \mathrm{~kg}$, (e) $360 \mathrm{~kg}$.

A $4.0-\mathrm{kg}$ object is subjected to two constant forces, $\vec{F}_1=(2.0 \mathrm{~N}) \hat{i}+(-3.0 \mathrm{~N}) \hat{j}$ and $\vec{F}_2=(4.0 \mathrm{~N}) \hat{i}-(11 \mathrm{~N}) \hat{j}$. The object is at rest at the origin at time $t=0$.

$(b)$ What is its velocity at time $t=3.0 \mathrm{~s}$ ?

A truck moves directly away from you at constant velocity (as observed by you while standing in the middle of the road). It follows that (a) no forces act on the truck, (b) a constant net force acts on the truck in the direction of its velocity, (c) the net force acting on the truck is zero, (d) the net force acting on the truck is its weight.

A $4.0-\mathrm{kg}$ object is subjected to two constant forces, $\vec{F}_1=(2.0 \mathrm{~N}) \hat{i}+(-3.0 \mathrm{~N}) \hat{j}$ and $\vec{F}_2=(4.0 \mathrm{~N}) \hat{i}-(11 \mathrm{~N}) \hat{j}$. The object is at rest at the origin at time $t=0$.

$(a)$ What is the object's acceleration?

The block-and-tackle system is released from rest with all cables taut. Neglect the mass and friction of all pulleys and determine the acceleration of each cylinder and the tensions $T_1$ and $T_2$ in the two cables.

A single constant force of magnitude $12 \mathrm{~N}$ acts on a particle of mass $m$. The particle starts from rest and travels in a straight line a distance of $18 \mathrm{~m}$ in $6.0 \mathrm{~s}$. Find $m$.

If one of the masses of the Atwood's machine in Figure $4-58$ is $1.2 \mathrm{~kg}$, what should be the other mass so that the displacement of either mass during the first second following release is $0.3 \mathrm{~m}$ ?

A particle is traveling in a straight line at a constant speed of 25.0 m/s. Suddenly, a constant force of 15.0 N acts on it, bringing it to a stop in a distance of 62.5 m. What is its mass?

An Atwood's machine as shown in figure consists of two masses, one of mass 3.00 kg and the other of mass 8.00 kg. When released from rest, what is the acceleration of the system?

A particle is traveling in a straight line at a constant speed of 25.0 m/s. Suddenly, a constant force of 15.0 N acts on it, bringing it to a stop in a distance of 62.5 m. What is the direction of the force?

The acceleration due to gravity on the Moon's surface is known to be about one-sixth the acceleration due to gravity on the Earth. Given that the radius of the Moon is roughly onequarter that of the Earth, find the mass of the Moon in terms of the mass of the Earth.

Suppose a test pilot is able to safely withstand an acceleration of up to 5.0 times the acceleration due to gravity (that is, remain conscious and alert enough to fly). During the course of maneuvers, he is required to fly the plane in a horizontal circle at its top speed of 1900 mi/h.

$(b)$ How long does it take him to go halfway around this minimum-radius circle?

Figure 8-44 shows the behavior of a projectile just after it has broken up into three pieces. What was the speed of the projectile the instant before it broke up: $(a) v_3,(b) v_3 / 3,(c) v_3 / 4,(d) 4 v_3$, (e) $\left(v_1+v_2+v_3\right) / 4 ?$

A 60-kg housepainter stands on a 15-kg aluminum platform. The platform is attached to a rope that passes through an overhead pulley, which allows the painter to raise herself and the platform (Figure 4-57).

$(b)$ When her speed reaches $1.0 \mathrm{~m} / \mathrm{s}$, she pulls in such a way that she and the platform go up at a constant speed. What force is she exerting on the rope now? (Ignore the mass of the rope.)