final Flashcards
Which has zero acceleration? A)an object at rest B)an object moving at constant velocity C)an object in equilibrium D)all of the above E)none of the above
D) All of the above. Acceleration is a change in speed and/or velocity.
A car traveling at 100 km/h strikes an unfortunate bug that splatters on the windshield. The force of impact is greater on the
A) car.
B) bug.
C) same for both
C) The same for both.
Newton’s Third Law. Every action has an equal and opposite reaction. Forces are equal and opposite.
The unit for weight is
A) Newton, N
B) kilogram, kg
A) Newton, N
Which one of the following is not in equilibrium?
A) a car on cruise control heading South
B) the Moon orbiting the Earth .
C) all of these
D) a book at rest on a table
B) The moon orbiting the earth. Orbiting = constant change in direction. Equilibrium = no change in direction or speed.
A kilogram (kg) is a measure of an object's A) force. B) weight. C) gravity. D) mass.
D) Mass.
When a baseball player hits a ball with a force of 1000 N, the ball exerts force on the bat of
A) 1000 N.
B) less than 1000 N.
C) more than 1000 N.
A) 1000 N.
Newton’s Third Law. Every action has an equal and opposite reaction. Forces are equal and opposite.
A moving object has A) energy. B) velocity. C) speed. D) all of the above
D) All of the above. (Energy = Kinetic Energy)
A box sliding across the floor eventually comes to a stop. Aristotle would explain this by saying
A)The box is reaching its natural state of motion - to be at rest.
B)The box has a net force on it.
C)The box’s inertia makes it stop.
D)The box encounters friction.
A)The box is reaching its natural state of motion - to be at rest
Although this is not true, this was Aristotle’s theory
An object that has twice as much mass as another object also has twice as much A)inertia. B)force. C)acceleration. D)velocity. E)all of the above
A)inertia. Inertia = an object’s tendency to resist a change in motion. If an object is twice as large, it takes twice the force to push, stop, or steer. If it’s half as large, it takes half the force to push, stop, or steer.
A 10-kg block is simultaneously pushed to the right with 20 N and to the left with 15 N. The net force on the block is A) 5 N to the left. B) 35 N to the right. C) 35 N to the left. D) 5 N to the right.
D) 5 N to the right. Think of one side as - and the other as +. The mass of the object doesn’t affect net force in this type of situation (No friction).
A 10-kg block is pushed across a friction-free horizontal surface with a horizontal force of 20 N. The acceleration of the block is A)2 m/s2. B)1 m/s2. C)5 m/s2. D)10 m/s2. E)none of the above
A) 2m/s^2.
Net Force/Mass = Acceleration
*m/s^2 = meters per second, squared
Compared with the mass of a certain object on Earth, the mass of the same object on the Moon is
A) more.
B) the same.
C) less.
B) the same.
Mass is always the same. Weight is relative to the force of gravity
While a car travels around a circular track at constant speed, its A) velocity is zero. B) both C) acceleration is zero. D) none of the above
D) None of the above. The car is turning, so it is accelerating. The car is moving, which means it has a speed and direction, so it has velocity (even though it’s not a constant velocity).
According to Galileo, the test of scientific truth is A) finding patterns in nature. B) experiment. C) logic. D) philosophical discussion.
B) Experiment
Which one of the following is not part of the Newton’s Third Law?
A) Two objects are required for a force interaction.
B) Accelerations are equal and opposite.
C) There are always two forces.
D) Forces are equal and opposite.
B) Accelerations are equal and opposite.
Newton’s Third Law discusses forces, not accelerations
Acceleration is _______________ proportional to mass.
A) directly
B) inversely
B) Inversely.
More Mass = More Inertia = Harder to change movement (speed or direction)
Acceleration = Change in movement (speed or direction)
As a ball falls, the action force is the pull of Earth on the ball. The reaction force is the
A)acceleration of the ball.
B)nonexistent.
C)air resistance acting against the ball.
D)pull of the ball on Earth.
E)none of the above
D)pull of the ball on Earth.
Newton’s Third Law. Every action has an equal and opposite reaction. Forces are equal and opposite.
Your weight is A) another word for your mass. B) the gravitational force by the Earth. C) a property of mechanical equilibrium. D) the same in all locations.
B) The gravitational force by the earth.
Weight is relative to gravitational force. You would weigh less on the moon than the earth, even though your mass is the same.
19) Inertia resists A) all of these B) acceleration C) turning D) changes in motion
A) All of these.
Acceleration is changing motion, which includes turning, speeding up, slowing down, or stopping.
Exert 100 J in 50 s and your power output is A)more than 4 W. B)2 W. C)1/2 W. D)1/4 W. E)4 W.
B) 2W
Power = Work / Time
Watts = Joules/Sec
A given net force propels an object along a straight-line path. If the mass were doubled, its acceleration would A)be half. B)double. C)quadruple. D)stay the same. E)none of the above
A) Be half.
Twice the mass means twice the force required to propel the object.
The force required to maintain an object at a constant velocity in free space is equal to A) the force required to stop it. B) zero. C) the mass of the object. D) the weight of the object.
B) Zero
Newton’s First Law. An object in constant velocity (equilibrium) without interference will stay in constant velocity (equilibrium)
23) Which one of the following has a zero net force?
A) a car doing donuts with constant speed
B) a book at rest on a table
C) the Moon orbiting the Earth .
D) a bird flying with constant speed .
B) a book at rest on a table
The net force of gravity and the table cancel out to 0.
A block is dragged at constant velocity across a level surface by a force of 6 N. What is the force of friction between the block and the surface? A) more than 6 N B) less than 6 N C) 6 N D) not enough information
C) 6N
To be at constant velocity, the net force must equal 0. Therefore the friction force and the pushing force must cancel eachother out.
25) A music console is pushed a distance of 2 m with a force of 20 N. The work done on the console is A) 40 J. B) 20 J. C) 10 J. D) 80 J. E) 2 J.
A) 40 J
Work = Force x Distance (Joules = Newtons x Meters)
Which one of the following objects is not in equilibrium?
A)The Earth orbiting the Sun
B)A car rounding a curve at a constant speed of 20 mph
C)A book falling down due to gravity alone
D)all of the above.
D) All of the above
All of these objects are accelerating, either through turning or speeding up.
If you do work on an object in half the time, your power output is
A) the same.
B) half.
C) twice.
C) Twice
Power = rate of work or work/time
A particle is being accelerated through space by a 10-N force. Suddenly the particle encounters a head-on second force of 10 N in the opposite direction. The particle with both forces acting on it
A)is brought to a rapid halt.
B)continues at the speed it had when it encountered the second force.
C)decelerates gradually to a halt.
D)theoretically tends to accelerate toward the speed of light.
E)none of the above
B) Continues at the speed it had when it encountered the second force.
When the forces meet, they will slow the particle, but then they will cancel out and the particle will enter equilibrium
Acceleration is _______________ proportional to net force.
A) directly
B) inversely
A) Directly
More force = more acceleration
30) A motor scooter accelerates when it A) decreases speed. B) changes direction. C) gains speed. D) all of the above.
D) All of the above
Acceleration = change in motion - speeding up, slowing down, turning, stopping.
Which of the following is not possible?
A)turning and not accelerating
B)moving with constant speed and accelerating
C)moving with constant speed but not constant velocity
D)all of these
The answer key says D, All of these. This is incorrect. The answer is A) turning and not accelerating.
Moving at a constant speed and turning would satisfy both B, and C. acceleration and non-constant velocity.
An object maintains its state of motion because it has A) speed. B) weight. C) mass. D) acceleration. E) all of these
C) Mass.
Mass = Inertia = inherent property to resist changes in motion
In class, I was able to pull a table cloth from underneath a plate without moving the plate. This best demonstrates that
A)the plate accelerated.
B)the plate has inertia.
C)gravity tends to hold the plate secure.
D)there is an action-reaction pair of forces.
E)none of these
B) The plate has inertia
Intertia = tendency to resist changes in motion (stayed where it was)
Which requires more work: lifting a 50-kg sack vertically 2 m or lifting a 25-kg sack vertically 4 m?
A)lifting the 25-kg sack
B)lifting the 50-kg sack
C)Both require the same amount of work.
C)Both require the same amount of work.
Work = Force X Distance
Joules = Newtons X Meters
Whenever the net force on an object is zero, its acceleration
A) is zero.
B) may be zero.
A) Is zero.
Acceleration requires force, to bring an object out of equilibrium.
Alternating current is normally produced by a A) generator. B) battery. C) Both D) Neither
A) Generator
A battery supplies a constant current (DC, Direct Current)
An alternator uses alternating KE input, producing alternating EPE output (AC, Alternating current)
The unit of resistance is the A) Coulomb. B) Ohm. C) Volt D) Joule E) Amp
B ) Ohm
The electric charge on all electrons
A) vary from atom to atom.
B) vary from ion to ion.
C) Are identical
C) Are identical
4)The source of electrons lighting an incandescent light bulb is A)atoms in the light bulb filament. B)the source voltage. C)the electric outlet. D)the power company. E)the wire leading to the lamp.
A) Atoms in the filament
Charges (electrons) flow, atoms stay put.
An electron and a proton
A)attract or repel depending on distance.
B)repel each other.
C)attract each other.
C) Attract
Opposite charges attract, same charges repel
The current in the wires of an AC A)changes direction. B)is nonexistent. C)remains relatively constant. D)changes via the inverse square law. E)none of the above
A) Changes direction
Hence the label alternating current
Maximum magnetic force on a current-carrying wire occurs when the wire is
A)in the same direction as the magnetic field.
B)at an angle other than 90° to the magnetic field direction.
C)opposite to the magnetic field direction.
D)perpendicular to the magnetic field direction.
E)none of the above
D)perpendicular to the magnetic field direction.
Magnetic and Electric fields are perpendicular to each other
The nucleus of an atom is charged A) negatively. B) positively. C) both D) none of the above
B) Positively
The nucleus consists of protons (+) and neutrons (no charge). Therefore the only charge present is positive
A difference between an insulator and a conductor is that a conductor has more A)protons than electrons. B)faster moving molecules. C)electrons than protons. D)energy than an insulator. E)none of the above
E) None of the above. A conductor has free-moving electrons, which an insulator does not have.
When a person experiences an electric shock, the origin of the electrons comprising the shock is A)the ground. B)likely a faulty lamp. C)the person's own body. D)a power plant. E)the electric field in the air.
C) The person’s own body.
Charges flow, atoms stay put. The atoms supplying the electrons are the ones that make up the body.
The electric force between charges depends on the
A) magnitude of electric charges.
B) separation distance between electric charges.
C) both
D) none of the above
C) Both
Magnitude of charges and Distance both affect the electric force between the charges