Midterm physics
The lowest temperature possible in nature is
-273 degrees C
When we talk about electric power we're talking
-joules per second. -watts
Absolute zero corresponds to a temperature of
0 K and -273 C
A bullet fired horizontally hits the ground in 0.5 s. If it had been fired with twice the velocity it would have hit the ground in
0.5s
The force of gravity acts on all apples on an apple tree. Some apples are twice as far from the ground. Such twice-as-high apples of the same mass, have
1/4 the weight
A woman who normally weighs 400 N stands on top of a very tall ladder so she is one Earth-radius above Earth's surface. What is her weigh there?
100 N
The temperature of boiling water is
100 degrees C or 212 degrees F 373.15 K
Two charges separated by 1 m exert a 1.0-N force on each other. If the charges are pushed to 0.25-m separation, the force on each charge will be
16N
If a projectile is fired straight up at a speed of 10 m/s, neglecting air resistance, the time it takes to reach the top of its path is
1s
When a battery does 24 J of work on 10 C of charge, the voltage it supplies is
2.4 V=w/c
A volume of helium gas has a temperature of 10°C. The same gas twice as hot has a temperature of
20 degrees c
The electric power of a lamp that carries 2 A at 120 V is
240 P=VxI
A length of wire has resistance R. The same wire twice as long has resistance
2R
The electric force on a 2-C charge is 60 N. How great is the electric field at the charge location?
30c
What would be the temperature of 50 g of 20°C water mixed with 80 g of 40°C water?
32.3
The temperature of melting ice is
32°F and 0°C
If the masses of two planets triples and the distance between reduces by half, the force between them would be
36 times as much
Two charges separated by 1 m exert a 1-N force on each other. If the magnitude of each charge is doubled, the force on each charge will be
4
A ball is thrown horizontally from the top of a tall cliff. Three seconds later, the ball has fallen a vertical distance of
45m
A projectile is launched straight upward at 50 m/s. If air resistance is negligible, its speed upon returning to its starting point is
50
What is the force of gravity on a 500-N woman standing on Earth's surface?
500 N
Increasing the temperature of 50 grams of water by 1°C requires
50cal
A stone is thrown horizontally from the top of a cliff. One second after leaving your hand it drops a vertical distance of
5m
The direction of an electric field is defined as the direction of force on a
A positively charged particle
As entropy in a system increases, energy within the system
Becomes less ordered
A hunter fires a bullet from a horizontally-held rifle while simultaneously dropping another bullet from the side of the rifle. Which bullet hits the ground first?
Both
The specific heat capacity of aluminum is more than twice that of copper. Place equal masses of aluminum and copper wire in a flame and the wire to heat up quickest will be
Copper
If Earth's mass decreased to one-half its original mass with no change in radius, your weight would
Decrease to one half
If your mass remained the same while the mass of Earth doubled while staying the same size, your weight would
Double
The electric field around an isolated electron has a certain strength 1 cm from the electron. The electric field strength 2 cm from the electron is
E=KQ/r^2 =E/4 None
Two charged particles repel each other with a force F. If the charge on one particle is doubled and the distance between them is doubled, the force will be
F/2
Which law of thermodynamics is a restatement of the conservation of energy as it applies to thermal systems?
First law (heat added = increase internal energy + external work done by the system)
A charge of 12. C passes through an electroplating apparatus in 2.0 min. What is the average current?
I=Q/t (convert to seconds) 120
What potential difference is required to cause 2.0 A to flow through a resistance of 8.0 Ω?
I=V/R V=IR 16v
If the mass of Earth somehow increased with no change in radius, your weight would
Increase
If the radius of the Earth somehow decreased with no change in mass, your weight would
Increase
If you heat a copper wire its electric resistance
Increases
Two objects move toward each other due to gravity. As the objects get closer and closer, the force between them
Increases
If the Sun were twice as massive,
It's pull on Earth would double and the pull of Earth on the Sun would double
To say that an object is electrically polarized is to say
Its charges have been rearranged
Compared to a single lamp connected to a battery, two identical lamps connected in series to the same battery will draw
Less current
Whether one object is warmer than another object has most to do with
Molecular kinetic energy
Compared to a single lamp connected to a battery, two lamps connected in parallel to the same battery will draw
More current
At some point between Earth and the Moon, the forces due to gravity on a space traveler would be the same. This point is
Near the moon
The power dissipated in a 4-ohm resistor carrying 3 A is
P-I^2xR 36
A power line with a resistance of 2 ohms draws a current of 80 A. The power dissipated in the line is
P=I^2xR 12800
What is the power rating of a device that draws 0.8 A when connected to 120 V?
P=IxV 96
How much current is in a 60-W light bulb connected to 120 V?
P=IxV I=0.5
The current in a 100-W bulb connected to a 120-V source is
P=IxV I=0.8
A pair of 60-W and 100-W incandescent lamps are intended for 120-V operation. Which lamp draws more current?
P=V^2/R R=V^2/P 100 because it has less resistance
A pair of 60-W and 100-W incandescent lamps are intended for 120-V operation. Which lamp has a larger resistance?
P=V^2/R R=V^2/P 60 has the largest resistance
A certain bulb with a resistance of 95 ohms and labeled "150 W" is designated for use in a
P=V^2/R V=(square root)RxP 120
As you comb your hair, electrons are rubbed onto the comb, which becomes
Positively charged
When you remove electrons from a metal cup, the cup becomes
Positively charged
Increasing the temperature of 80 grams of water by 2°C requires
Q=MCT 160 cal
When the distance between two charges is halved, the electric force between the charges
Quadruples
The length of a certain wire is kept same while its radius is doubled. What is the change in the resistance of this wire?
R=(resistivity)xLength/(pi)r^2 reduced by a factor of 4
Roll a bowling ball off the edge of a table. As it falls, its horizontal component of motion
Remains constant
Which law of thermodynamics addresses the direction of heat flow?
Second law (Heat never spontaneously flows from a cold substance to a hot substance.)
For each degree a volume of air at 0°C is cooled, its volume
Shrinks by 1/273
If the masses of two planets doubles and the distance between them also doubles, the force between them would be
The same
A very massive object A and a less massive object B move toward each other under the influence of gravity. Which force, if either, is greater?
The same according to newton's third law
A piece of iron and a cup of water both have the same temperature. If they are heated so the thermal energy of each doubles,
The water will have the higher temperature. lower heat capacity
A projectile is fired horizontally. With no air resistance it maintains its horizontal component of velocity because
There is no horizontal force
Two lamps, one with a thick filament and one with a thin filament, are connected in series to a battery. The voltage is greater across the lamp with the
Thin filament
Which law of thermodynamics states that no system can reach absolute zero?
Third law
The motion of molecules that most affects temperature is
Translation
An Earth satellite is simply a projectile freely falling around the Earth.
True
If the same quantity of heat is added to both a 1-liter and a 2-liter container of water, the temperature change of water in the 1-liter container will be
Twice
Consider two planets in space that gravitationally attract each other. If the mass of one planet is doubled, and the distance between them doesn't change, then the force between them is
Twice as much
Consider two planets in space that gravitationally attract each other. If the masses of both planets are doubled, and the distance between them doesn't change, then the force between them is
Twice as much
Compared to the mass of a proton, the mass of the electron is
Very much less
Inside a freely falling elevator your
Weight is Zero
The electric resistance of a superconductor is
Zero
In the vacuum of outer space, there is no
atmospheric pressure
A rock is thrown upward at 50° with respect to the horizontal. As it rises, its vertical component of velocity
decreases
When the distance between two stars doubles, the force between them
decreases by 1/4
A positive ion has a deficiency of
electrons
According to Newton, the greater the masses of interacting objects, the
greater the gravitational force between them.
If the Earth had twice its present radius and twice its present mass, what would happen to your weight?
half
When the distance between two stars decreases by half, the force between them
increases four times as much
The length of a certain wire is doubled while its radius is kept constant. What is the change in the resistance of this wire?
it doubles
The greatest expansion of water occurs when
it turns to ice
Heat energy is measured in units of
joules and calories
At absolute zero, a substance has
no more energy to give up
A difference between an insulator and a conductor is that a conductor has more
nothing
Which is the smallest unit of measurement for temperature?
one farenheit
The nucleus of an atom is charged
positively
A pair of positively-charged plastic straws tend to
repel
Heat is thermal energy that flows due to
temperature differences
Heat is thermal energy that matter
transfers
A metal ring with a gap in it is shaped like the letter C. When heated, the gap becomes
wider