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.