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