Science Chapter 4

1.

1 point

A force of 11 N is applied to the handle of a wedge. As the input force moves the handle 0.3 m, it does 3 J of work the pry a can open. What is the wedge's efficiency?

1.1%

91%

81%

9.9%

2.

1 point

A machine requires 420 J of work to do 230 J of work in lifting a box. What is the device's efficiency?

0.5%

190%

70%

55%

3.

1 point

If two sprinters compete in a race, the faster sprinter develops more of what?

Power

Work

Both of the above

4.

1 point

An ax is an example of what simple machine?

5.

1 point

In which of the following is NO work accomplished?

Walking up stairs

Lifting a backpack

Pushing a door

None of the above

6.

1 point

Can you make work output greater than work input?

Yes

No

7.

1 point

What makes a machine classify as a compound machine?

Greater efficiency

It is made up of multiple simple machines

Has an ideal mechanical advantage greater than 1

Moving parts

8.

1 point

An example of a compound machine is…

Bicycle

Ramp

Crowbar

Seesaw

9.

1 point

A water filled bucket weighing 15 N is raised 2 m in 1 s. How much power is produced?

30 W

0.13 J

7.5 W

18 J

10.

1 point

To reach an efficiency of 100%, what must be done?

Use electricity to power the machine

Friction must be eliminated

Work input must increase

Increase the work rate of the machine

11.

1 point

Which of the following is true according to the law of conservation of energy

Energy cannot be created

Energy cannot be destroyed

Energy can change from one form to another

All of the above

12.

1 point

The actual mechanical advantage of a machine…

Is less than the ideal mechanical advantage

Decreases as the input distance increases

Cannot be less than 1

Increase with increased friction

13.

1 point

A machine is used to multiply what?

Force

Work

Power

14.

1 point

The efficiency of a machine is always ____ than 100%

15.

1 point

To accomplish work, force must act in what way?

In the opposite direction of the force applied

In the same direction of the force applied

16.

1 point

The SI unit for power is…

Joule

Watt

Newton

Newtonian meter

17.

1 point

A 25 N brick is lifted 5 m off of the ground. How much work is done?

125 J

5 J

30 W

0.2 W

18.

1 point

A ____ is an inclined plane wrapped around a cylinder

19.

1 point

A 20 kg bike is moving at a speed of 2 m/s. What is its kinetic energy?

80 J

40 J

22 J

10 J

20.

1 point

Why is the gravitational potential energy of an object 1 m above the moon less than its GPE 1 m above Earth?

The acceleration of gravity is less on the moon

Gravity is faster on the moon

The object's mass is less on the moon

The object's weight is more on the moon

21.

1 point

Any forces not acting in the direction of an object's motion fails to accomplish ______

22.

1 point

How does a machine make work easier?

By increasing the work done by the machine

By increasing the amount of energy used

By changing the direction of the force you apply

By decreasing the amount of work you do

23.

1 point

What is the unit for work?

Newton

Watt

Joule

Meters

24.

1 point

A machine's power measures its…

Work done

Strength

Work rate

Force produced

25.

1 point

What is the energy of motion?

26.

1 point

Reducing friction in a machine results in what?

Decreases work output

Increases the efficiency

Decreases it's ideal mechanical advantage

Increases the ideal mechanical advantage

27.

1 point

A steering wheel is an example of what simple machine?

28.

1 point

If a force of 10 N is exerted to lift an object 0.9 m, how much work is done?

0.1 J

9.0 J

90.0 J

10.9 J