Physics Final exam
The ballistics pendulum below is used to determine the velocity of a bullet. The value of v' can be calculated using the following equation Correct!
(2gh)1/2
The only way that a heat engine can have an efficiency of 1, is if the engine's cold temperature is .
0oK
Carly places one end of a steel bar in a Bunsen flame and the other end in an ice cube. By what factor is the rate of heat flow changed when the bar's cross-sectional area is doubled?
2
An object moves in a circular path with constant speed v. Which of the following statements is true concerning
Both its velocity and acceleration are changing.
When considering human metabolism in terms of the 1st Law of Thermodynamics, which of the following represents the metabolic rate?
DU / Dt
T/F A watt is a unit of energy
F
T/F Angular acceleration and centripetal acceleration are the same.
F
T/F If the distance between 2 masses is tripled, the force of gravity between the masses will be one third as great
F
T/F If the speed of an object is doubled, its kinetic energy will be doubled
F
T/F Increasing the impact time in a collision increases the impact force.
F
T/F Newton's Second Law states that net force acting on any mass will produce an acceleration
F
T/F Newton's Third Law the "action" and "reaction" are on the same object
F
T/F The coefficient of friction increases as the Normal force increases
F
T/F The constant "G" in Newton's Universal Law of Gravitation is 9.8 m/s^2
F
T/F The escape velocity from the Earth is infinite
F
T/F The moment of inertia of a disk is greater than the moment of inertia of a ring.
F
T/F The moment of inertia of an object is a vector.
F
T/F The weight of an object is the same on the Moon as on the Earth
F
T/F Three equal masses collide as shown This was an elastic collision.
F
T/F if the speed of a car is doubled, its stopping distance will be doubled
F
For the answer to #35 to be correct, all three must have the same mass.
False
What happens to a given mass of water as it is cooled from 4oC to zero?
It expands
The ballistics pendulum shown is used to determine the velocity of a bullet. Which of the following is not true.
KEA = KEB
Which of the following statements is true?
Objects do not contain heat.
Which of the following involves the greatest heat transfer?
One gram of steam at 100oC changing to water at 100oC.
Perpetual motion machines of the second kind are not allowed by the
Second Law of Thermodynamics
Momentum is conserved in both elastic and inelastic collisions.
T
T/F An object is in rotational equilibrium when the net torque on the object is zero.
T
T/F Angular velocity is a vector.
T
T/F In an elastic collision the maximum impact force is approximately equal to twice the average impact force.
T
T/F Kinetic energy is conserved in elastic but not in inelastic collisions.
T
T/F Momentum is a vector but kinetic energy is a scalar.
T
T/F The acceleration of an object is 0 if the net force on it is 0
T
T/F The coefficient of static friction (us) is never less than the coefficient of kinetic friction (uk)
T
T/F The force of friction increases as the Normal force increases
T
T/F The inertia of an object is the same on the moon as on the Earth
T
T/F The mass of an object is a quantitative measure of its inertia
T
Three equal masses collide as shown Which of the following statements is true
The magnitude of v3 is greater than the magnitude of v2.
A 400 g mass, m1, is balanced at the end of a 100,g meter stick as shown. If r1 is increased, the system rotates counterclockwise. Assume the center of mass of the meter stick is at the 50 cm mark and m1 is at the 0 cm mark. The clockwise torque is supplied by the meter stick.
True
The center of mass of an object can be inside or outside the object.
True
What is the mathematical relationship between the coefficient of volume expansion, b, for given material and its corresponding coefficient of linear expansion, a?
b = 3a
The answer to #38 is based on the fact(s) that
both Angular Momentum is conserved during the rotation and the Moment of Inertia of the student changes.
The maximum theoretical thermodynamic efficiency of a heat engine operating between hot and cold reservoirs is a function of which of the following?
both hot and cold reservoir temperatures
You can increase the Torque applied by a wrench by
both increasing the length of the wrench and increasing the force on the wrench.
According to the second law of thermodynamics, which of the following applies to the heat received from a high temperature reservoir by a heat engine operating in a complete cycle?
cannot be completely converted to work
Heat is transferred from the equator to the polar regions primarily by
convection
Which one of the following processes of heat transfer requires the presence of a fluid?
convection
A student is rotating at a constant angular velocity while holding two weights as shown. If the weights are moved outward, the angular velocity will
decrease
Entropy is a measure of the ___________ of a system.
disorder
Which of the following choices best corresponds to what is required by the second law of thermodynamics for any process taking place in an isolated system?
entropy increases
Motion in which gravity is the only force acting is called
free fall
In cloud formation, water vapor turns into water droplets which get bigger and bigger until it rains. This will cause the temperature of the air in the clouds to:
get warmer
Andrea and Chuck are riding on a merry-go-round. Andrea rides on a horse at the outer rim of the circular platform, twice as far from the center of the circular platform as Chuck, who rides on an inner horse. Chuck's translational speed is
half of Andrea's
Evaporation cools the liquid that is left behind because the molecules that leave the liquid during evaporation:
have greater than average speed.
Physics tries to answer the question ______ does the universe work?
how
If global warming continues, it's likely that some ice from the polar ice caps of the Earth will melt and the water will be distributed closer to the Equator. If this occurs, would the length of the day (one revolution)
increase
A steel plate has a hole drilled through it. The plate is put into a furnace and heated. What happens to the size of the inside diameter of a hole as its temperature increases?
increases
The stability of an object can be increased by __ the size of the base.
increasing
According to the first law of thermodynamics, the sum of the heat gained by a system and the work done on that same system is equivalent to which of the following?
internal energy change
Twenty grams of a solid at 70°C is place in 100 grams of a fluid at 20°C. Thermal equilibrium is reached at 30°C. The specific heat of the solid:
is more than that of the fluid
The absolute temperature of an ideal gas is directly proportional to which of the following properties, when taken as an average, of the molecules of that gas?
kinetic energy
A cart of mass 2.0 kg, moving at a constant velocity of 6.0 m/s collides head on with a stationary 1.0 kg cart. The two carts stick together and move off in a straight line at velocity v'. The total kinetic energy of the system after the collision was ___ before the collision .
less than
The stability of an object can be increased by __ the center of mass.
lowering
During an isobaric process which one of the following does not change?
pressure
How does the heat energy from the sun reach us through the vacuum of space?
radiation
If one's hands are being warmed by holding them to one side of a flame, the predominant form of heat transfer is what process?
radiation
Which type of heating causes sunburn?
radiation
On a sunny day at the beach, the reason the sand gets so hot and the water stays relatively cool is attributed to the difference in which property between water and sand?
specific heat
Heat flow occurs between two bodies in thermal contact when they differ in what property?
temperature
A solid ball, a disk, and a ring all roll down an incline as shown. Assume that all start from rest from the same starting point on the incline. The one that reaches the bottom first is
the ball
The reason for the answer to #35 is primarily due to the fact that
the moment of inertia of the ball is least.
Andrea and Chuck are riding on a merry-go-round. Andrea rides on a horse at the outer rim of the circular platform, twice as far from the center of the circular platform as Chuck, who rides on an inner horse. When the merry-go-round is rotating at a constant angular speed, Chuck's's angular speed is
the same as Andrea's
A 1.0 kg ball drops vertically onto a floor, hitting with a speed of vi = 24 m/s. It rebounds with a speed of vf = -24 m/s. The ball is in contact with the floor for 0.12 s. The direction of the total momentum of the system after the collision was
to the right