PHYS Midterm Review

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A centimeter is

.01 m

The longest of the following is

0.00001 km

Mars is about 1.5 times as far from the sun as the earth and its mass is about 0.1 times the earth's mass. Relative to the gravitational force the sun exerts on the earth, the force it exerts on Mars is about

0.044 as much

A crane exerts an upward force of 200 N on a 20-kg crate. The crate's upward acceleration is

0.2 m/s^2

A force that gives a 2-kg object an acceleration of 1.6 m/s^2 would give an 8-kg object an acceleration of

0.4 m/s^2

The share of solar energy in the supply of electricity in the United States is approximately

1 percent

The mass of a 2,200-lb elephant is

1,000 kg

The prefix giga stands for

1,000,000,000

A car whose mass is 1600 kg (including the driver) has a maximum acceleration of 1.2 m/s^2. If three 80-kg passengers are also in the car, its maximum acceleration will be

1.04 m/s^2

A 1-kg mass has a KE of 1J when its speed is

1.4 m/s

A car starts from rest and reaches a speed of 15 m/s in 10s. Its acceleration is

1.5 m/s^2

The mechanical advantage of a pair of scissors might be

1/2

A 300-g ball is struck with a bat with a force of 150 N. If the bat was in contact with the ball for 0.02 s, the ball flew off at

10 m/s

The proportion of the world's electricity that comes from nuclear energy is roughly

10 percent

In 6 min a person running at 10 km/h covers a distance of

1000 m

In 6 min a person running at 10 km/h covers a distance of `

1000 m

A net horizonal force of 2000 N is applied to an 800-kg car at rest. The car's speed after 5 s will be

12.5 m/s

A boat whose velocity through the water is 20 km/h is moving in a river whose current is 6 km/h relative to the riverbed. The velocity of the boat relative to the riverbed must be between

14 and 26 km/h

A 1-kg object is moving at 10m/s. To double it's kinetic energy, its speed should be increased to approximately

14 m/s

A horizontal force is applied to a 2-kg ball on a smooth table. The ball's speed is 8 m/s when it has gone 4 m. The magnitude of the force is

16 N

The breaking force needed to bring a 4000-kg truck to a stop from a speed of 20 m/s in 5 s is

16,000 N

A nautical mile (nm) is 6076 ft long, and a knot (kn) is a unit of speed equal to 1 nm per hour. How many feet per second does a 10-kn boat movie through the water?

17 f/s

A person is 5 ft 8 in tall. This is equivalent to

173 cm

In the first 3 s after a car starts from rest with an acceleration of 4 m/s^2 it will travel

18 m

The minimum force that must be applied to a machine with a mechanical advantage of 5 in order to lift a 100-kg crate is

196 N

A 100-kg astronaut ejects 4g of gas from her propulsion pistol at a speed of 50 m/s. Her recoil speed is

2 mm/s

The size of a picture is given as 84 cm by 255 cm. Since (84)(255) = 2.142 exactly, the area of the picture is expressed with the correct number of significant figures?

2.1 m^2

The number of cubic centimeters in a cubic foot is about

2.8 x 10^4

A 500-g ball moves in a circle 40 cm in radius at a speed of 4 m/s. The centripetal force on the ball is

20 N

In a good wind, a modern large wind turbine might have a power output of

2000 kW

If present trends in population and greenhouse gas emissions continue, the earth's surface temperature will increase by at least a catastrophic 4C by the year

2100

The minimum number of unequal forces whose vector sum can equal zero is

3

When a ton of coal burns, it loses 3.3 x 10^-7 kg of mass. The energy given off is

3.0 x 10^10 J

A 1200-kg car is traveling at 10m/s on a road such that the maximum frictional force between its tires and the road is 4000 N. The minimum turning radius of the car is

30 m

The 2.5-kg head of an ax exerts a force of 80 kN as it penetrates 18 mm into the truck of a tree. The speed of the ax head when it strikes the tree is

34 m/s

Average energy use per person in the United States today is about

4 times the world average

A stone dropped from a cliff reaches the ground in 4 s. The stone's speed is then

40 m/s

The normal lifetime of a nuclear power reactor is

40-60 years

When its brakes are applied, a car moving at 10 m/s undergoes an acceleration of -1.2 m/s^2. How far does the car travel before it comes to a stop?

42 m

A 150-kg safe on frictionless casters is being raised 1.20 m to the bed of a truck using planks 4.00 m long. The force needed to push the safe up os

441 N

A ship travels 20 km to the south and then 40 km to the west. The ship's displacement from its starting point is

45 km

A 50-kg person weighs

490 N

An 800-kg car moving at 80km/h overtakes a 1200-kg car moving at 40 km/h in the same direction. If the two cars stick together, the wreckage has an initial speed of

56 km/h

Six kJ of work is used to lift an object to a height of 100 m. The object's approximate mass is

6 kg

A ball thrown upward at 30 m/s will reach the ground after about

6.0 s

The mass equivalent of 6.0 MJ is

6.7 x 10^-11 kg

A woman whose mass is 60 kg on the surface is in a spacecraft at a height of 2 earth radii above the earth's surface. Her mass there is

60 kg

Which of the following sets of displacements might be able to return a car to its starting point?

60, 120, 180, and 240 km

A car moving at 10 m/s undergoes an acceleration of 1.2 m/s^2. In the next 5 s the car travels

65 m

A ball of mass 200 g is whirled in a circle at the end of a string 100 cm long whose breaking strength is 100 N. Neglecting gravity, the maximum speed of the ball is approximately

7 m/s

A 3000-kg truck accelerates from 10m/s to 30 m/s in 8 s. The net force on the truck is

7500 N

A car starts from rest with a constant acceleration for 5 m/s^2. How much time does the car take to cover the first 160 m?

8 s

When a 430-g soccer ball is kicked, the impact lasts for 0.04 s. In order for the ball to fly off at 8 m/s, the force of the kick must be

86 N

A man whose mass is 80 kg on the earth's surface is in a spacecraft at a height of 2 earth radii above the earth's surface. His weight there is

87 N

Which of the following is (are) not a unit of power?

Joule-second

The discovery that the planetary orbits are ellipses rather than circles are ellipses rather than circles were made by

Kepler

A planet that cannot be seen with the unaided eye is

Neptune

The scientist who showed that gravity accounts for Kepler's laws of planetary motion was

Newton

Which of the following statements is not true?

The United States has less than 5 percent of the world's coal reserves

Which of the following statements is true?

The moon is chiefly responsible for the tides, with the sun's influence modifying the tidal range

World energy use in 2035 is expected to be

almost 150 percent of what it was in 2015

Relative to what she weighs on the earth, an astronaut visiting another planet

any of these choices, depending on the planet

The sun

attracts light waves passing by

In fracking, natural gas trapped in rock formations is released by

breaking up the rock with water under high pressure

International agreements thus far

call for promises from all countries to reduce their use of fossil fuels

Algae are able to make diesel fuel through photosynthesis using as a raw material

carbon dioxide

At present, the source of most electricity from moving water is

dams in rivers

After electricity generation and heating, the next most important contribution to greenhouse gasses in the atmosphere comes from

deforestation

This time at which a given star rises above the horizon each night is

earlier than the night before

Relative to the stars, the moon seems to move

eastward

A bowling ball rolling on level ground at the speed v strikes a basketball at rest. The basketball moves off in the original direction of the bowling ball

faster than v while the bowling ball continues slower than v

The stars in a constellation

form a pattern in the sky as seen from the earth

The speed of an object moving in a circle is doubled. The centripetal force needed is

four times as much as before

If the moon were half as far from the earth as it is now, the gravitational force it exerts on the earth would be

four times its present value

Stars and planets are round because

gravity forces them into this shape

The weight of an object is

greater at the poles than at the equator

Living things

have evolved throughout earth's history

Rolling a ball up an inclined plank required an amount of work proportional to the

height the ball is raised

When the sun, the earth, and the moon are all in line,

high tides are higher than usual and low tides are lower than usual

Of these sources, which is responsible for the most energy today?

hydropower

When first proposed, a scientific idea is usually called a

hypothesis

The earth's atmosphere is mainly heated by

infrared light radiated by the earth

According to the general theory of relativity, gravitation

is a distortion in space-time

The speed of a planet in its orbit

is highest when it is closest to the sun

When the speed v of an object of mass m approaches the speed of light c, its kinetic energy

is more than 1/2 mv^2 and can exceed 1/2 mc^2

The escape speed needed for an object to leave the earth permanently

is more than the minimum speed it needs to become an earth satellite

Astrology

is nonsense

When the speed of an object is doubled,

it's momentum is doubled

A bullet is fired upward. As it rises,

its mass remains the same while its weight decreases

What distinguished the scientific method from other ways of looking at the natural world is

its reliance on experiment and observation

If a shell fired from a cannon explodes in midair,

its total KE increases

On a molecular level heat is

kinetic energy

Which of the following units could be associated with a vector quantity?

km/s^2

A regularity observed data or relationship between different quantities is usually called a

law

Burning coal does not cause the release into the environment of

less carbon dioxide per unit of energy than other fossil fuels

In the formula E=mc^2, the symbol c represents the speed of

light

Scientific theories

must be constantly reviewed to see whether they are in accord with new experimental observation

In the United States, the lowest cost per unit of electrical output in the immediate future would come from using which of these energy sources?

natural gas

Fuel cells

need continuous supplies of fuel

A week is the time needed for

none of the choices are correct

Of the following energy sources, the one most likely to run out of reserves first is

oil

The period of the earth's orbit around the sun is

one year

The watt is a unit of

power

A promising but expensive method of preventing the escape into the atmosphere of carbon dioxide from fossil fuel power plants is to

pump it into underground reservoirs

When a skater pulls in her arms to turn faster, her angular momentum

remains the same

In the distant past, the length of the day in

shorter than 24 hours

The length of the year is

slightly more than 365 days

A golf ball and ping-pong ball are dropped in a vacuum chamber. When they have fallen halfway down, they have the same

speed

In which one or more of the following is the earth assumed to be the center of the universe

the Ptolemaic system

In which one or more of the following is the earth assumed to be the center of the universe?

the Ptolemaic system

The two countries together responsible for about 40 percent of the world's carbon dioxide emissions are

the United States and China

If the earth had no moon,

the average tidal range would be smaller

A day is the time needed for

the earth to turn completely on its axis

A factor that helps prevent the widespread use of hydrogen as a fuel is

the need to first separate hydrogen from one of its chemical compounds, such as water

a year is the time needed for

the sun to migrate completely around the sky

What never changes when two or more objects collide is

the total momentum of all the objects

Two-thirds of the world's oil production is used for

transport fuel

In most parts of the world high tides occur approximately

twice a day

The radius of the path of an object moving in a circle at a constant speed is halved. If the speed remains the same, the centripetal force needed is

twice as much as before

The world's fastest-growing source of clean energy is

wind

If the earth were to revolve on its axis slower than it does today, its shape

would be closer to a perfect sphere


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