Physical Science 10B Unit 2 Test Review

According to the First Law of Thermodynamics, the amount of work done by a heat engine = the amount of ___?

thermal energy added to the engine minus the waste heat

As the temperature of an object rises, so does the ___?

thermal energy of the object

Which of the following states that absolute zero cannot be reached?

third Law of Thermodynamics

In which of the following is no work done?

none of the above; work is done by: climbing stairs, lifting books, pushing shopping carts

Which of the following increases when an object becomes warmer?

thermal energy

A 750-W motor might also be rated as a ___?

1-horsepower motor

If you have to apply a force of 40 N of force on a crowbar to lift a rock that weights 400 N, what is the actual mechanical advantage of the crowbar?

10

If you have to apply 30 N of force on a crowbar to lift a rock that weighs 330N, what is the AMA of the crowbar?

11

A 100-m long ski lift carries skiers from a station at the foot of a slope to a second station 40m above. What is the IMA of the lift?

2.5

A motor with an efficiency of 75% must apply 240 J of useful work. What amount of work must be supplied to the motor?

320 J

A 12-kg sled is moving at a speed of 3.0 m/s. At which of the following speeds will the sled have twice as much kinetic energy?

4.2 m/s

A small 20-kg canoe is floating downriver at a speed of 2 m/s. What is the canoe's kinetic energy?

40 J

If you exert a force of 500N to walk 4m up a flight of stairs in 5s, how much power do you use?

500 W

If you exert a force of 10.0 N to lift a box a distance of 0.75m, how much work do you do?

7.5 J

If you exert a force of 700 N to walk 6 m up a flight of stairs in 6 s , how much power do you use?

700 W

A 4-kg cat is resting on top of a bookshelf that is 2m high. What is the cat's gravitational potential energy relative to the floor if the acceleration due to gravity is 9.8 m/s^2?

78 J

A small dog is trained to jump straight up a distance of 1.2m How much kinetic energy does the 7.2-kg dog need to jump this high?

85 J

A mechanical device requires 400 J of work to do 340 J of work in lifting a crate. What is the efficiency of the device?

85%

A slab of granite has a mass of 1400.0 grams. The specific heat of granite is 0.840 j/g* degrees C. How much heat must be absorbed to raise the granite slab's temp. by 75 degrees C?

88.2 kJ

How can you make the work output of a machine greater than the work input?

none of the above: NOT by: decreasing friction, increasing input force, increasing output distance

Which of the following is an example of an object with elastic potential energy?

all of the above; a wind-up toy that has been wound up, a compressed basketball, a stretched rubber band

Which of the following statements is true according to the Law of Conservation of Energy?

all of the above; energy cannot be created, energy cannot be destroyed, energy can be converted from one form to another

Which of the following statements is a consequence of the equation e= mc^2?

all of the above; energy is released when matter is destroyed, mass and energy are equivalent, the Law of Conservation of Energy must be modified to state that mass and energy are conserved in any process

Which of the following happens in a steam engine?

all of the above; fuel is burned outside the engine, heat is converted into work, hot steam pushes a piston

Which of the following is an example of a wheel and axle?

an automobile steering wheel

Based on your knowledge of energy conservation, which of the following statements is true?

both a and b; manufacturers can increase a light bulb's energy efficiency by using technology that increases the amount of electromagnetic energy the bulb converts from a given amount of electrical energy and energy can be conserved by turning off lights when they are not in use

Matter is needed to transfer thermal energy by ___?

both conduction and convection

How can a machine make work easier for you?

by changing the direction of your applied force

How is the work output of a machine calculated?

by multiplying the output force by the output distance

Walking converts what type of energy into mechanical energy?

chemical

The energy stored in gasoline is ___?

chemical energy

A drawback of solar energy is that it ___?

depends on the climate

The ideal mechanical advantage of a wheel and axle is found by ___?

dividing the radius of the wheel by the radius of the axle

What is transferred by a force moving an object through a distance?

energy

Work is a transfer of ___?

energy

A machine is a device that can multiply ___?

force

A delivery man pushes the button to ring the doorbell. Which of the following forms of energy is NOT involved in this process?

gravitational

Nonrenewable energy resources include all of the following EXCEPT

hydrogen fuel cells

Reducing friction in a machine ___?

increases its efficiency

An inclined plane reduces the effort force by ___?

increasing the distance through which the force is applied

A force that is exerted on a machine is called the ___ force

input

The actual mechanical advantage of a machine ___?

is less than the ideal mechanical advantage of the machine

A machine is classified as a compound machine if it ___?

is made up of two or more simple machines that operate together

The power of a machine measures ____

its rate of doing work

An object's gravitational potential energy is NOT directly related to which of the following?

its speed

The mechanical energy of an object equals its ___?

kinetic energy plus its potential energy

A machine ___?

makes work easier to do, changes the size of the force needed, and can change the distance/direction of the force

The equation E = mc^2 relates energy and ___?

mass

Which of the following materials conducts heat well?

metal

In which of the following does Einstein's famous equation apply?

nuclear fission and fusion reactions

The ideal mechanical advantage of a pulley system is equal to the ___?

number of rope segments supporting the load

About 746 watts = how many horsepower?

one

Energy from the sun reaches Earth mostly by ___?

radiation

The gravitational potential energy of an object is always measured relative to the ___?

reference level from which the height is measured

A fluid that vaporizes and condenses inside the tubing of a heat pump is called the ___?

refrigerant

Fossil fuels currently account for the majority of the world's energy use because they are ___?

relatively inexpensive and readily available

The efficiency of a machine is always less than 100% because ___?

some work input is lost to friction

What is biomass energy?

the chemical energy stored in living things

A force acting on an object does no work if ___?

the force is not in the direction of the object's motion

Why is the gravitational potential energy of an object 1 meter above the moon's surface less than its potential energy 1 meter above Earth's surface?

the moon's acceleration due to gravity is less

Which of the following statements is true?

to increase power, you can increase the amount of work you do in a given amount of time, or you can do a given amount of work in less time