Tue Jan 31 Today Reviewhw 5.5 Read p293-295

(p280) 83,87,91 (p307-9) 56, 61,76,81,82

ch 10-11 test next Tue. or Wed.!

The formula for kinetic energy is:

K=(mv2)/2

K=(mv)2/2

K=2mv2

K=(mg)/h

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1. K=(mv2)/22. K=(mv)2/23. K=2mv2

4. K=(mg)/h

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The SI units for energy and work are:

Newtons

Watts

Joules

Amperes

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1. Newtons2. Watts3. Joules4. Amperes

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Kinetic energy is a ____ quantity

Tensor

Scalar

Vector

Negative

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1. Tensor2. Scalar3. Vector4. Negative

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The transfer of energy by mechanical means is called _______.

Heat

Mach

ination W

ork Fo

rce

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1. Heat2. Machination3. Work4. Force

Work is done when:

A force

acts t..

.

A hot object

t...

A force

acts p...

You sleep on t..

.

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1. A force acts through a distance.

2. A hot object touches a cold object.

3. A force acts perpendicular to a displacement

4. You sleep on the job.

Energy stored in an object that has been lifted in a gravitational field is called:

Elasti

c potent...

Gravita

tional ...

Chemical p

oten...

Thermal e

nergy...

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1. Elastic potential energy

2. Gravitational potential energy

3. Chemical potential energy.

4. Thermal energy.

If an object’s speed doubles its kinetic energy:

Quadruples

Doubles

Is cu

t in half..

.

Doesn’t c

hange

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1. Quadruples2. Doubles3. Is cut in half.4. Doesn’t change

The kinetic energy of a 4.0 kg object moving at 3.0 m/s is:

12 J 18 J

36 J 48 J

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1. 12 J2. 18 J3. 36 J4. 48 J

How much work is done if you push a 5.0 kg box 12 meters across the floor while

applying a 10.0 N force?

50 J 60 J

120 J 600 J

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1. 50 J2. 60 J3. 120 J4. 600 J

How much work do you do if you lift a 6.0 kg object 50 cm up?

None 3.0 J

30 J

3.0 kJ

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1. None2. 3.0 J3. 30 J4. 3.0 kJ

_____ describes how quickly energy is transferred.

Kinetic energy

Velocity

Power

Pressure

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1. Kinetic energy2. Velocity3. Power4. Pressure

The SI units of power are:

Joules

Teslas

Pascals

Watts

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1. Joules2. Teslas3. Pascals4. Watts

A Watt is equal to

N m J s

N/m2 J/

s

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1. N m2. J s3. N/m2

4. J/s

I have 1.2 kW microwave. How much electrical energy is converted if I heat something on high for 30 seconds?

40 J 400 J

600 J 36 kJ

0% 0%0%0%

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1. 40 J2. 400 J3. 600 J4. 36 kJ

If the power output of a motor is 65 W, how long does it take to do 195 J of work?

1.95 seco

nds

3.0 seco

nds

260 seco

nds

3.5 hours

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1. 1.95 seconds2. 3.0 seconds3. 260 seconds4. 3.5 hours

________ is where we decide to set gravitational potential energy to zero.

The null zone

Outer space

The reference

...

On top of s

pag...

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1. The null zone2. Outer space3. The reference level4. On top of spaghetti

Which of the following is a conservative force?

Fricti

on

Thrust

Gravity

Air resis

tance

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1. Friction2. Thrust3. Gravity4. Air resistance

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A 4.0 kg object is moving has 72 J of kinetic energy when it is 3.0 m above the reference level. Its speed is

2.0 m/s

5.0 m/s

6.0 m/s

192 m/s

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1. 2.0 m/s2. 5.0 m/s3. 6.0 m/s4. 192 m/s

A 4.0 kg object has 72 J of kinetic energy when it is 3.0 m above the reference level.

Its total mechanical energy is

0.0 J 72 J

120 J 192 J

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1. 0.0 J2. 72 J3. 120 J4. 192 J

A 4.0 kg object has 72 J of kinetic energy when it is 3.0 m above the reference level. Once it falls down to the reference level it will have a kinetic

energy of

72 J 120 J

192 J 0.0 J

0% 0%0%0%

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1. 72 J2. 120 J3. 192 J4. 0.0 J

Simple machines can NOT

Multiply th

e f...

Multiply th

e w...

Change the dir..

.

Change the sp

e...

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1. Multiply the force that is exerted

2. Multiply the work that is done

3. Change the direction a force is exerted

4. Change the speed

The mechanical advantage of a simple machine describes

How much

the m

...

How much

the d...

How much

the f..

.

How much

the p...

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1. How much the machine multiplies the work you do

2. How much the distance is multiplied

3. How much the force is multiplied

4. How much the power is multiplied

The efficiency of a machine describes:

The ratio of th

e output...

The ratio of th

e output f.

..

The ratio of th

e output ..

.

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1. The ratio of the output work to the input work

2. The ratio of the output force to the input force

3. The ratio of the output distance to the input distance

If a machine has a mechanical advantage of 5.0 how much force must you exert to lift a 60 kg object?

60 N 120 N

300 N 3.0 kN

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1. 60 N2. 120 N3. 300 N4. 3.0 kN

An input of 8.0 kJ of work is is provided to a machine that exerts a 2.0 kN force through a distance of 3.0

meters. What is the efficiency?

25%37.50%

75%133%

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1. 25%2. 37.5 %3. 75%4. 133%

A pulley is used to raise a 2.0 kg object 50 cm off of the table. The work done BY the machine is:

1.0 kJ 100 J

10.0 J 1.0 J

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1. 1.0 kJ2. 100 J3. 10.0 J4. 1.0 J

A pulley is used to raise a 2.0 kg object 50 cm off of the table. The person pulling the string exerts a force of 8.0 N through a distance of 2.0 m. How much work is done

by the person?

1.0 J

10.0 J 4.0 J

16 J

0% 0%0%0%

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1. 1.0 J2. 10.0 J3. 4.0 J4. 16 J

A pulley is used to raise a 2.0 kg object 50 cm off of the table. The person pulling the string exerts a force of 8.0 N through a distance

of 2.0 m. The mechanical advantage of the machine is

4.2.5 2. .5

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1. 4.02. 2.53. 2.04. 0.50

A pulley is used to raise a 2.0 kg object 50 cm off of the table. The person pulling the string exerts a force of 8.0 N through a distance

of 2.0 m. The efficiency of the machine is

31%63%

100%160%

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1. 31%2. 63%3. 100%4. 160%

A pulley is used to raise a 2.0 kg object 50 cm off of the table. The person pulling the string moves their hand

2.0 m. What is the IMA of the machine?

4.2.5 .25 10.

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1. 4.02. 2.53. 0.254. 10.0