Chapters 10-11

Question 1

A wheelbarrow is an example of a class ……. lever.

Answer 1

Class 2 lever

Question 2

A pry bar is an example of a class ….. lever.

Answer 2

Class 1 lever

Question 3

A fly swatter is an example of a class ….. lever.

Answer 3

Class 3 lever

Question 4

A pair of scissors is an example of a class ….. lever.

Answer 4

Class 1 lever

Question 5

The equation IMA =2(pie)r/p is used to find the IMA of a …..

Answer 5

Screw

Question 6

For a simple machine, the ratio of output force to input force is …..

Answer 6

AMA

Actual mechanical advantage

Question 7

For a simple machine, the ratio of input distance to output distance is …..

Answer 7

IMA

Ideal mechanical advantage

Question 8

What is defined as the time rate of doing work?

Answer 8

Power

Question 9

The SI unit for frequency is the ……

Answer 9

hertz (Hz).

Question 10

A freely swinging mass hanging by a thin, massless connector is called a(n) …… pendulum.

Answer 10

Simple

Question 11

An object that moves back and forth over the same path and completes every round trip in the same amount of time is in …… motion.

Answer 11

Oscillatory motion

Question 12

The product of force and displacement is ……

Answer 12

Work

Question 13

The SI unit of work is the …..

Answer 13

joule (J).

Question 14

An object oscillating along a straight line caused by a restoring force proportional to its displacement is exhibiting ……

Answer 14

Simple harmonic motion

Question 15

Any effort that produces motion is called …..

Answer 15

Work

Question 16

A lever with the load and the input force on opposite sides of the pivot point is called a ….. class lever.

Answer 16

class 1 lever

Question 17

The SI unit of power is the …..

Answer 17

watt (W).

Question 18

The ….. mechanical advantage is what the mechanical advantage would be if there were no energy losses due to friction or other causes.

Answer 18

Ideal

Question 19

The point at which a lever pivots is called the ……

Answer 19

Fulcrum

Question 20

One horsepower is equal to ….. ft.(•)lb/s.

Ask me about this one

Answer 20

550

Question 21

True/False

When a weight lifter lowers the weights, he is doing (positive) work.

Answer 21

Negative

Question 22

A series of pulleys working in conjunction is called a (block and tackle).

Answer 22

True

Question 23

The IMA of any simple machine will be (greater) in value than the machine’s AMA.

Answer 23

True

Question 24

An object in uniform circular motion has a constant (velocity).

Answer 24

Speed

Question 25

If a centripetal force is the action, a (normal) force is the reaction.

Answer 25

centrifugal

Question 26

The (amplitude) of oscillation is the maximum displacement of an oscillation.

Answer 26

True

Question 27

The (period) of oscillation is how many oscillations occur in a given time.

Answer 27

frequency

Question 28

When you (double) the length of a pendulum, you also double the period of the pendulum.

Answer 28

quadruple

Question 29

As the mass of a pendulum increases, the period (decreases).

Answer 29

Increases

Question 30

As the driving frequency approaches the natural frequency of vibration, the amplitude of vibration (increases).

Answer 30

True

Question 31

When the natural frequency of vibration is close to the driving frequency, the result is (simple harmonic motion).

Answer 31

resonance

Question 32

Equations
Write the correct equation to:

Determine work when the force and motion are not along the same line of action.

Answer 32

W= Fd cos(-) theta

Question 33

Equation for

The law of levers.

Answer 33

F(i)r(i)= F(o)r(o)

(i) input lever arm
(o) output lever arm

Question 34

Equation for the centripetal acceleration of an object.

Answer 34

ac (centripetal acceleration) = v^2
———
r

Question 35

Short answer

Define the three classes of levers by telling where their pivot point, output, and input are in relation to each other.

Answer 35

If the input force and output force are located on opposite sides of the fulcrum, this is a class one lever.

It is a class two lever if the output force (load) is between the fulcrum and the input force; and it is a class three lever if the input force is between the fulcrum and the load.

Question 36

Write three of the four laws of a pendulum.

Answer 36

The period of the pendulum…

(1) depends on the square root of it length.
(2) is inversely dependent on the square root of the rate of acceleration due to gravity.
(3) does not depend on its mass.

Question 37

Explain why major highway curves are banked.

Answer 37

Major highway curves are banked to protect motorists from flipping their cars. Banked curves help prevent vehicles from losing traction caused by centripetal force between the tires and the road.

Question 38

Problems

Two children are holding onto opposite ends of a rope. The one on roller skates is being swung around in circles. If the moving child weighs 75 lb and he attains a constant speed of 12 ft/s, and if the rope is 10 ft long, how much tension is in the rope? Neglect friction.

Answer 38

F(centripetal)= m•v^2
———
r

Question 39

As a boy pulls a sled carrying his sister, he exerts a force of 2.6 lb at an angle of 30 degrees with the ground. How much work does he do if he pulls her at constant speed for exactly one-half mile (2640 ft).

Answer 39

W=Fd cos(-) theta
1 J= 0.7376 ft•lb
5280 ft.= 1 mile= 1609 meters
1 lbs= 4.448 N

Question 40

A spring vibrates with a period of 0.50 s when a mass of 3.0 kg is placed on it. What is the spring constant for this spring?

Answer 40

T=2(pi)*square root of m/k

Question 41

A 75 lb boy and a 65 lb girl play on a seesaw. The seesaw is 14 ft long and is pivoted exactly in the middle. If the girl sits on the end of her side, where must the boy sit to make the seesaw balance?

Answer 41

F(i)r(i)=F(o)r(o)

Question 42

The pendulum of a grandfather clock is supposed to have a period of 2.0 s. How long should the pendulum be in meters?

Answer 42

T= 2(pi)*square root of l/g