Physics
If there is 10 N force acting downward on an object and 15 N force acting upward, what is the net force on the object?
5 N upward
What is the angular velocity, ω, of an object that has a radius of 5 meters and is moving at a linear velocity, v, of 25 meters/second?
5 radians/second
Which of the following is considered a vector quantity?
55 kilometers per hour north
What is the rotational KE of a 5 kg cylinder with a 10 meter radius and an angular velocity of 5 rad/s if all its mass was concentrated in the center?
625 Joules Using the equation Icylinder with mass at center = 0.1 mr^2 and plugging that moment of inertia into our rotational KE (= 1/2 I ω^2) gives us a rotational KE of 625 Joules. KE = (1/2)(0.1 ∗ 5 ∗ 10^2)(5^2) = 625 J
If a car is rolling naturally downhill without the engine running, what energy transfer is happening?
Gravitational potential energy is changing into kinetic energy.
Which of the following is an example of a force?
Gravity Wind A hand pushing
Which of the following is a full definition of uniform circular motion?
It is motion in a circle at a constant speed; this happens because of a centripetal force, a force pointing towards the center of a circle.
If the distance between two objects is doubled, and the mass of one of the objects is doubled, what happens to the gravitational force?
It reduces to a half.
If you increase the distance between two objects by a factor of three, what happens to the force between them?
It reduces to a ninth.
What is Newton's Law of Gravitation?
It says that every object in the universe attracts every other object.
If a stationary object has a 5 Nm clockwise torque applied to it, add a 5 Nm counter-clockwise torque, how will the motion of the object change?
It will not rotate at all.
If a stationary object has a 10 Nm clockwise torque applied to it, add a 15 Nm counter-clockwise torque, how will the motion of the object change?
It will rotate more and more counter-clockwise.
A car moving on a perfectly straight road is an example of which kind of motion?
Linear motion
Which of the following is an assumption of Newton's Universal Law of Gravitation that doesn't EVER apply to an extended object?
Masses can be taken as point masses.
A planet's average distance from the sun is equal to the
Semimajor axis
In which of the following kinds of motion are the displacement, velocity and acceleration graphs sinusoidal in shape?
Simple harmonic motion
If you double the mass of the block attached to a spring-block oscillator, what will happen to the frequency of the oscillation?
The frequency will reduce, but not by as much as a half.
For an inclined plane with friction, what is the net force?
The sum of the two parallel vectors
What is net force?
The vector sum of all forces acting on an object
According to Newton's third law of motion, when you lean on a brick wall what is happening?
The wall is pushing back on you. You are pushing on the wall. The force of the wall pushing is equal to the force of you pushing.
How can a moving object be in equilibrium?
There is no net force on the object
What three assumptions do we make about ideal fluids?
They are incompressible, have laminar flow, and are non-viscous
What causes a change in an object's state of motion?
Unbalanced forces
You push on a factory door with a force of 5 newtons, at a distance of 10 meters from the hinge. Your friend pushes the door from the other side with a force of 10 newtons at a distance of 5 meters from the hinge. What is the overall torque you're applying to the door?
Zero torque.
Which of the following terms is the rate at which the velocity of an object is changing?
acceleration
The type of friction that acts on a falling object is called _______.
air resistance
Which of the following terms is the change in position of an object?
displacement
A book sliding across a desk will come to a stop because of the force of _______.
friction
When finding the forces of an object on an inclined plane, which of these vectors is separated into its two different components?
gravity
Without friction, ______ would not be possible on earth.
motion
The book sliding across the desk is an example of _______ friction.
sliding
An object moving in uniform circular motion has a constant _____, but a changing _____.
speed; velocity
What is kinematics?
study of motion
You push on a door with a force of 5 newtons, at a distance of 0.5 meters from the hinge. What is the torque you're applying to the door?
2.5 newton meters.
What does the equation of continuity tell us about movement of an ideal fluid?
As the area decreases the speed increases
The planets in our solar system all have ___orbits
Elliptical
A mass on a spring, with mass 10 kilograms and spring constant 5 N/m. The maximum displacement of the spring is 0.5 meters. What is the displacement after 1.2 seconds? (The stopwatch starts as the spring passes through the equilibrium position (middle). Make sure your calculator is in the radians mode.)
0.374 meters T = (2π x √ m)/ k - k = 5N/m - m = 10kg x = Asin(ωt) - t = 1.2 sec - A = 0.5 m - f = 1/T - ω = f(2π)
Which of the following orbital eccentricities is NOT an elliptical orbit? 0 0.1 0.5 0.999 1
1 elliptical orbit- an orbit with an eccentricity less than 1
A cylinder with a uniformly distributed mass is placed on a 10 meter high incline. What would be its linear velocity when it reaches the ground?
11.43 m/s equation of linear velocity of the cylinder being equal to √(4/3*g*h), giving us the answer of 11.43 m/s.
Example of velocity
12 meters per second south
A spring with a spring constant of 100 N/m completes one oscillation in 2.4 seconds. What is the mass attached to the spring? T = (2π x √ m)/ k
14.6 kg T = 2π√(m/k) T2 = 4π2 (m/k) m = (kT2) / 4π2 m = (100)(2.4)2 / 4π2 m = 14.6 kg
Which of the following would be considered a scalar quantity?
212 degrees Celsius
A planet is orbiting its star at a maximum radius of 1.2 x 10^7 meters. If the mass of the star is 2 x 10^30 kg, what is the time period of the orbit? T = sqrt [ (4 * π^2 * R^3) / GM ]
22.6 seconds
If it takes 25 N to push a car, the friction between the road and the car's tires is ________.
25 N
Object A has a mass of 3 x 10^10 kilograms, and object B has a mass of 8 x 10^10 kilograms. If they are 8,000 meters apart, what is the gravitational attraction between them? (G = 6.67 x 10^-11) Fg = (G * M1 * M2) / d^2.
2500 N
A ball on a string in uniform circular motion has a velocity of 8 meters per second, a mass of 2 kilograms, and the radius of the circle is 0.5 meters. What is the centripetal force keeping the ball in the circle?
256 N Fc=mv^2 / r
What is the magnitude of the amplitude of a spring-mass system where the angular frequency is π rad/s, and the mass is at a displacement of 4 cm at 1 second? (Hint: You will need to adapt your equation to cosine as you are starting to measure time (t = 0) at maximum displacement, not in the center of the oscillation.)
4 cm x = A cos(ωt) 4 = A cos(π (1)) A = 4 / (cos π) A = -4 cm, which gives an amplitude of 4 cm
A planet is orbiting its star at a maximum radius of 1.2 x 10^7 meters. If the mass of the star is 2 x 10^30 kg, and the current radius is 0.9 x 10^7 meters, what is the velocity of the orbit? v = sqrt [ G*M*(2/r - 1/a) ]
4.3 x 10^6 meters per second
If a pendulum has a length of 5 meters, what is the time period of the pendulum? (2π x √ l)/ G
4.5 seconds
You lift a 3kg dumbbell from the ground until it is above your head, at a height of 1.5 meters. How much energy did you use in the process? GPE = mgh
44 Joules
What is the linear velocity of an object if its angular velocity is 15 rad/s and its diameter is 10 meters?
75 m/s ω = v/r therefore v = ω ∗ r, We are given diameter, so we have to find the radius. r = diameter/2 = 10/2 = 5 m v = 15 rad/s ∗ 5 m = 75 m/s
What is the flow rate of water through a hose that fills a 55-gallon aquarium in 5.7 minutes?
9.6 gal/min Q = ΔV / Δt
A 10 kg bowling ball is lifted from the ground to a height of 1 meter. Assuming the bowling alley is on Earth, how much gravitational potential energy does it now have? GPE = mgh
98 Joules
If all of the objects have around the same mass, which of the following objects has the most gravitational potential energy? A chair set on the ground A book on a high shelf on the first floor of a house A ball stuck on the roof of a two-story house A cat investigating a basement
A ball stuck on the roof of a two-story house Since all the objects have the same mass, the GPE is based on the height the object is off the ground.
Which one of the following is NOT an example of acceleration? A car going around a curve in the road at a constant speed A car driving in a straight line that changes speed from 20mph to 40mph A car driving in a straight line at a constant speed A car going around a curve that changes speed from 20mph to 40mph
A car driving in a straight line at a constant speed
What is motion?
A change in position over time
What is a free-body diagram?
A force vector diagram A picture or sketch used to show the forces acting on an object, with arrows representing the forces
What is the spring constant?
A number that represents how stretchy a spring is. A bigger spring constant means the spring is stiffer.
A vector is
A quantity containing a magnitude and a direction
Scalar is
A quantity that does not involve direction
A speed limit sign along a highway in Montana says 70 mph. This information on this sign is an example of
A scalar quantity
In general, what are Kepler's Laws?
A series of laws that describe the elliptical motion of orbiting bodies.
What is an inclined plane?
A tilted surface
What is torque?
A twisting force that tends to cause rotation.
If a planet has an orbital eccentricity equal to 0.70, then its orbit is
A very elongated ellipse
What is a pendulum?
A weight hung from a stationary point such that it can swing freely back and forth.
Who came up with the special theory of relativity?
Albert Einstein
Which of the following statements about special relativity is FALSE?
An assumption of special relativity is that the laws of physics are the same in all reference frames.
What kind of relationship does gravity follow with distance?
An inverse-square relationship
Within the context of gravitational forces, what is an extended object?
An object that is not spherical, or uniform in shape, and cannot be treated as a point mass.
What is an elliptical orbit?
An orbit between a circle and a parabola in shape (but not including a parabola).
What is simple harmonic motion?
Any motion where a restoring force is applied that is proportional to the displacement, in the opposite direction of that displacement.
In what direction do normal forces act?
At 90 degrees to the surface
At what point in a pendulum's motion is the acceleration greatest?
At maximum displacement (the outer edges).
Where in the oscillating motion of a mass on a spring, is the net force the greatest?
At the greatest compression and greatest extension.
How do we know that gravitational potential energy exists?
Because when you drop a ball, it starts to move, and this energy has to come from somewhere.
How was time dilation proven?
By experimenting with atomic clocks and a jet plane.
What is the name of the force that keeps an object in circular motion?
Centripetal force
In which of the following kinds of motion can an object have a constant speed and still be accelerating?
Circular motion
Where do you weigh more, at the Dead Sea or on Mount Everest?
Dead Sea
This is the extent to which an orbit deviates from a circle
Eccentricity
A __is one of two fixed points from which an ellipse can be generated
Focus
In order for an object to move, which of the following must act on it?
Force
Which of Newton's Laws of Motion is most useful in figuring out mass and weight?
Newton's Second Law is the idea that force is equal to mass times acceleration. This law is the most useful for figuring out mass and weight.
Which of the following is not a consequence of special relativity?
Nothing is certain; everything is relative.
In what direction do frictional forces act?
Opposite to the direction of motion
In which direction does the normal force always act?
Perpendicular to the surface
A baseball being hit for a home run is an example of which kind of motion?
Projectile motion
In what direction does gravity act?
Straight down
What is mass?
The amount of matter present in something Uniform assuming nothing happens to alter the object Found by dividing the force of an object by its acceleration
In the train thought experiment, two beams of light are fired from the center of a moving train car: one beam of light towards the front of the train and one towards the back. From the perspective of a person on the side of the tracks, watching the train, which beam of light reaches the edge of the train car first?
The beam going towards the back of the train car.
What is weight?
The force that gravity has on an object
When no friction acts, what is the net force equal to?
The parallel vector component
What makes a pendulum simple?
The pendulum has one, single point mass, and the mass of the string is negligible.
Why does the speed of an ideal fluid change as it passes through a narrower area of tube?
The same amount of fluid must go through this point as everywhere else in the same time interval
What is the mass of objects in space?
The same as the mass on Earth
What is the difference between a scalar and a vector?
Vectors have a direction and scalars do not.
What is the equation of continuity?
v1 * A1 = v2 * A2
Which of the following terms is the rate of change of position of an object?
velocity
The rotational kinetic energy of an object is NOT dependent on which of these variables?
volume