An elephant and a feather fall through the air. The force of air resistance is
1) greater on the feather
2) greater on the elephant
3) the same on each
because
4) the feather weighs less.
5) the elephant encounters more air because of his greater size and speed.
6) each is under the influence of gravitational force alone.
[Ques. 2] When the spool is pulled to the left, it accelerates toward the
1) right,
2) left,
which illustrates the fact that
3) for every force there is an equal and opposite reaction force.
4) net force and acceleration act in the same direction.
[Ques. 3] In referring to how much matter a body contains, we use the term
1) volume
2) mass
3) weight
and the force of gravitational attraction upon a body is
4) weight.
5) volume.
6) mass.
[Ques. 4] Neglecting all types of friction, if two identical sleds, one empty and the other with four heavy passengers, start sliding down a hill together, the heavier sled will get to the bottom
1) before the empty car,
2) after the empty car,
3) at the same time as the empty car,
while in the presence of air resistance, the heavier car will get to the bottom
4) before the empty car.
5) after the empty car.
6) at the same time as the empty car.
[Ques. 5] A 100-newton sack of potatoes falls from an airplane. As velocity of fall increases, air resistance also increases, and when air resistance equals 100 N, the acceleration of the sack is
1) zero
2) 5 m/s2
3) 10 m/s2
4) 100 m/s2
and the velocity of the sack will be
5) 0 m/s.
6) 5 m/s.
7) 10 m/s.
8) 100 m/s.
9) constant.
[Ques. 6] A heavy man and a light man parachute together from a high-flying plane. The first to attain zero acceleration will be the
1) light man
2) heavy man
3) both will attain zero acceleration at the same time.
because
4) the gravitational force on each man is the same.
5) of the lesser gravitational force acting on the lighter man.
6) air resistance will eventually counterbalance the weights of both men.
7) the lighter man will not have to fall for as long a time before air resistance equals his weight.
[Ques. 7] You would have the most quantity of gold if it weighed 1 N on the
1) Moon.
2) Earth.
3) planet Jupiter.
4) would be the same on each.
This is because
5) on the Moon a greater mass of gold is required for the gravitational force to equal 1 N.
6) weight and mass are directly proportional to each other.
7) gravitational force per mass is greatest on the most massive planet.
[Ques. 8] A baseball is thrown straight upward. At the very top of its trajectory its instantaneous velocity is zero and its acceleration is
1) zero.
2) 10 m/s2.
3) between zero and 10 m/s2.
4) none of these.
We can better understand this by noting that when it is at its highest point
5) there momentarily is no motion.
6) its rate of change of motion is still 10 m/s2.
7) although its velocity is not changing, its direction is.
[Ques. 9] A person is attracted toward the center of Earth by a gravitational force of 500 N. The force with which Earth is attracted toward the person is
1) 500 N
2) infinitesimally small
3) billions and billions of tons
principally because
4) the forces in question make an action/reaction pair.
5) the mass of the person is negligible compared to the mass of Earth.
6) Earth itself weighs billions and billions of tons.
7) of inertia.
[Ques. 10] In the absence of air resistance, a boulder and a pebble dropped from rest will fall with equal
1) forces of gravity.
2) accelerations.
3) energies.
4) all these.
The reason that this quantity is not greater for the boulder than the pebble is that
5) both the boulder and the pebble fall at the same speed.
6) the initial potential energies of each is the same.
7) gravitational force acting on each is the same.
8) the greater gravitational force on the boulder acts on a correspondingly greater mass.
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