# Power calculations

Question 11 pts

A 50-N object falling in air experiences 30 N of air resistance. The amount of net force on the falling object is

0 N.

50 N.

80 N.

20 N.

Flag question: Question 2

Question 21 pts

A 10-N falling object encounters 4 N of air resistance. The net force on it is

10 N.

6 N.

0 N.

4 N.

Flag question: Question 3

Question 31 pts

A 20-N falling object encounters 20 N of air resistance. The net force on it is

0 N.

4 N.

6 N.

20 N.

Flag question: Question 4

Question 41 pts

Given that two forces of 10 N and 17 N act horizontally (one dimension) on an object, the net force must

be 7 N.

be either 7 N or 27 N.

be 27 N.

lie between 0 N and 27 N.

Flag question: Question 5

Question 51 pts

What is the net force on a box that is being pushed to the right with 60 N of force while, at the same time, being pushed to the left with 20 N of force?

80 N.

40 N.

20 N.

0 N.

Flag question: Question 6

Question 61 pts

The equilibrium rule Fnet = 0 applies to objects in constant motion in a straight line. This statement is

false.

true.

Flag question: Question 7

Question 71 pts

An object moving with constant speed in a straight line, or is at rest, or is in equilibrium has zero acceleration. This statement is

false.

true.

Flag question: Question 8

Question 81 pts

Whenever the net force on an object is zero, its acceleration

not enough information

and speed are the same.

is zero.

may be zero.

Flag question: Question 9

Question 91 pts

Burl and Paul have a total weight of 1300 N. The tensions in the ropes that support the scaffold they stand on add to 1700 N. The weight of the scaffold itself must be

500 N.

800 N.

400 N.

600 N.

Flag question: Question 10

Question 101 pts

The force of friction on a sliding object is 40 N. The applied force needed to maintain a constant velocity is

40 N.

more than 40 N.

less than 40 N.

impossible to tell

Flag question: Question 11

Question 111 pts

A bucket of cement is raised by a rope at constant speed at a construction site. Compared with the force of gravity on the bucket, the upward force supplied by the rope is

greater

impossible to tell

equal

less

Flag question: Question 12

Question 121 pts

The forces acting on the object at rest are equal in magnitude and are in the same direction so that the net force is zero. This statement is

false

true

Flag question: Question 13

Question 131 pts

When you toss a coin straight up, it moves upward, turns around, and drops. During all this time the acceleration of the coin is

zero throughout its up and down motion.

downward and constant.

first decreasing, then increasing.

upward and constant.

Flag question: Question 14

Question 141 pts

A stone is thrown vertically upward. At the top of its vertical path the force acting on it is

only the force due to gravity.

both due to gravity and air resistance.

due to air resistance.

zero

Flag question: Question 15

Question 151 pts

If you drop an object, it will accelerate downward at a rate of 10 m/s2. If you instead throw it downward, its acceleration (in the absence of air resistance) will be

not enough information

less than 10 m/s^2.

greater than 10 m/s^2.

10 m/s^2.

Flag question: Question 16

Question 161 pts

A constant net force on a railroad car produces constant acceleration AND constant velocity. This statement is

false

true

Flag question: Question 17

Question 171 pts

A 10-kg brick and a 1-kg book are dropped in a vacuum. The force of gravity on the 10-kg brick is

the same as the force on the 1-kg book.

10 times as much as the force on the 1-kg book.

5 times as much as the force on the 1-kg book.

Zero

Flag question: Question 18

Question 181 pts

A 10-kg block is pushed across a friction-free horizontal surface with a horizontal force of 20 N. The acceleration of the block is

5 m/s^2.

10 m/s^2.

2 m/s^2.

1 m/s^2.

Flag question: Question 19

Question 191 pts

If an object falls with constant acceleration, the velocity of the object must

continually increases by the same amount each second.

continually decrease.

be constant also.

continually change by varying amounts.

Flag question: Question 20

Question 201 pts

A force of 1 N accelerates a 1-kg mass at 1 m/s2. The acceleration of a 2-kg mass acted upon by a force of 2 N is

twice as much.

half as much.

the same.

Flag question: Question 21

Question 211 pts

A 1000-kg car accelerates at 2 m/s2. What is the net force exerted on the car?

500 N.

2000 N.

1500 N.

1000 N.

Flag question: Question 22

Question 221 pts

A ball is thrown vertically upward. At the top of its vertical path, its velocity is