PHYS Midterm Review
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
