Physics EXAM 1 (Hard Questions)
A car moving at 15 m/s comes to a stop in 3 s. Its acceleration is
-5 m/s2
A centimeter is
.01
The shortest of the following is
.1 mil
A force that gives a 2-kg object an acceleration of 1.6 m/s2 would give an 8-kg object an acceleration of
.4 m/s2
The work you do in raising an orange from your waist to your mouth is roughly
1 J
The share of solar energy in the supply of electricity in the United States is approximately
1%
Prefix Giga
1.000.000,000
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%
The mass of a 2,200-lb elephant is
1000 kg
In 6 min a person running at 10 km/h covers a distance of
1000 m
An airplane reaches its takeoff speed of 60 m/s in 30 s starting from rest. The time it spends in going from 40 m/s to 60 m/s is
10s
A net horizontal 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 snail travels 45 cm in 20 min. Its average speed is
135 cm/h
The braking 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 person is 5 ft 8.0 in. tall. This is equivalent to
173 cm
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 40-kg boy climbs a vertical ladder at 0.5 m/s. His power output is
196 W
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 as
2.1 m^2
The number of cubic centimeters in a cubic foot is about
2.8 x 10^4
The mass of a sack of potatoes whose weight is 200 N is
20.4 kg
A net force of 10 N gives an object an acceleration of 5 m/s2. What net force would give the same object an acceleration of 1 m/s2?
2N
The minimum number of unequal forces whose vector sum can equal zero is
3
When a ton of coal burns, it loses 3.3 × 10-7 kg of mass. The energy given off is
3.0x 10^10 J
The speed of a 1000-kg car whose KE is 450 kJ is
30 m/s
Arrange the following planets in the order of their distance from the sun.1. Venus2. Mars3. Earth4. Mercury
4,1, 3, 2
Arrange these fuels in increasing order of energy given off per gram when they are burned.1. gasoline2. hydrogen3. coal4. ethanol
4,3,1,2
A 1-N weight has a KE of 1 J when its speed is
4.4 m/s
A stone dropped from a cliff reaches the ground in 4 s. The stone's speed is then
40 m/s
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
Average energy use per person in the United States today is about
4x the world average
Six kJ of work is used to lift an object to a height of 100 m. The object's approximate mass is
6 kg
The mass equivalent of 6.0 MJ is
6.7 x 10^-11 kg
An 800-kg car moving at 80 km/h collides head-on with a 1200-kg car moving at 40 km/h in the opposite direction. If they stick together, the wreckage now has an initial speed of
8 km/h
The contribution of fossil fuels to world energy supply is about
87%
A car starts from rest with a constant acceleration of 5 m/s2. How much time does the car take to cover the first 160 m?
8s
Relative to what she weighs on the earth, an astronaut visiting another planet
Any
Mercury absorbed in the body damages the nervous system and is especially harmful to unborn children. Pollution by mercury is one result of burning
Coal
The time at which a given star rises above the horizon each night is
Earlier than the night before
Living things
Evolved throughout the earth's history
The discovery that the planetary orbits are ellipses rather than circles was made by
Kepler
A regularity in observed data or a relationship between different quantities is usually called a
Law
A week is the time needed for
None
Of the following energy sources, the one most likely to run out of reserves first is
Oil
The Sun
attracts light waves passing nearby
In fracking, natural gas trapped in rock formations is released by
breaking up the rock with water under high pressure
To prevent it from tumbling in flight, a projectile such as a football is sent off spinning. The physical principle involved is
conservation of angular momentum
The time needed for a planet to orbit the sun
depends on the average distance of the planet from the sun
Relative to the stars, the moon seems to move
eastward
If the Antarctic and Greenland icecaps melt completely, sea level will rise
everywhere over 50m
According to Newton's third law of motion,
for every face there is an equal and opposite reaction force but each acts on a different object
Stars and planets are round because
gravity forces them into this shape
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
Environmental concerns are the most important factor in limiting the expansion of which of the following energy sources?
hydropower
of these sources which is responsible for the most energy today?
hydropower
When first proposed a scientific idea is usually called a
hypothesis
The speed of a planet in its orbit
is highest when it is closest to the sun
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,
its momentum is doubled
If a shell fired from a cannon explodes in midair
its total KE increases
Which of the following units could be associated with a vector quantity?
km/s^2
Compact fluorescent light bulbs are more efficient than incandescent light bulbs
last longer
Burning coal does not cause the release into the environment of
less carbon dioxide per unit of energy than other fossil fuels
When the speed v of an object of mass m approaches the speed of light c, its kinetic energy
more than 1/2 mv^2 and can exceed 1/2
A jumper whose weight is w presses down on the floor with the force F and leaves the floor as a result. The force the floor exerted on the jumper was
more than w and more than F
Fuel cells are
need continuous supplies of fuel
Since 1900 the world's population has increased by
over 400 percent
The object in the sky that lies very nearly on an extension of the earth's axis is
polaris
Which of these statements is not true for oil from tar sands?
producing oil from tar sands involves emitting less carbon dioxide than extracting crude oil does
On a rainy day the maximum frictional force between a car's tires and a certain level road surface is reduced to half its usual value. The maximum safe speed for rounding a curve is
reduced to 71% of its usual value
When a skater pulls in her arms to turn faster, her angular momentum
remains the same
Gravity is not
responsible for holding atoms and molecules together
Length of the year is
slightly more than 365
Kepler Modified
the Copernican System
If the earth had no moon
the average tidal range would be smaller
An object moving in a circle at constant speed is accelerated
toward the center of the circle
2/3 worlds oil production is used
transport oil
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 perfect shape
The British unit of length closest to the meter is the
yard
The time needed for a car whose speed is 60 km/h to travel 800 m is
.8 min
A 2-kg book is held 1 m above the floor for 50 s. The work done is
0
A 90-kg llama has an average power output of 80 W. The minimum time the llama can go up a hill 500 m high is
1.5 h
A weightlifter raises a 200-kg barbell through a height of 2 m in 2.2 s. The average power he develops during the lift is
1.78 kW
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-N weight has a PE relative to the ground of 1 J when it is at a height of
1m
Which one or more of the following pairs of displacements cannot be added to give a resultant displacement of 2 m?
1m and 4m
A moose weighing 3 kN is standing still. The force the ground exerts on the moose is
3 kN
A ball thrown upward at 30 m/s will continue to rise for about
3.0 s
It seems possible that a serious effort to improve the efficiency of electricity use in the United States could reduce its consumption of electric energy by
50%
A ball thrown upward at 30 m/s will reach the ground after about
6s
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 sedentary person requires about 6 million J of energy per day. This rate of energy consumption is equivalent to about
70 W
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
What distinguishes the scientific method from other ways of looking at the natural world is
its reliance on experiment and observation
If a spaceship 100 m long when at rest on the earth were to travel at nine-tenths the speed of light, its length as measured by an observer on the earth would be
less than 100 m
In which one or more of the following is the earth assumed to be the center of the universe?
the Ptolemaic System
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
An optimistic projection for 2100 suggests that 9.6 billion might then be the population of
the world
The radius of the path of an object moving in a circle at constant speed is halved. If the speed remains the same, the centripetal force needed is
twice as much as before
International agreements thus far
call for promises from all countries to reduce their use of fossil fuels
The sun exerts a gravitational force on the earth and the earth exerts a gravitational force on the sun. The force the earth exerts
can be considered either as the action or as the reaction force
According to the general theory of relativity, gravitation
curvature of space-time
