A. always opposite in direction to their relative motion
When a conventional car is braked to a stop, its kinetic energy is transformed to
At the do it yourself car wash on Route 17 you can have 3 minutes of "high pressure spray" to clean your vehicle. What is the pressure of the water when it hits your shiny fenders?
C. One atmosphere (100,000 Pa). The extra pressure from the machine was converted to velocity when the water exited the nozzle
Which temperature scale has 373 degrees as the boiling point of water?
The maximum speed a practical single stage rocket can achieve is
C. greater than the speed of its exhaust plume but less than is required for most satellite launches
To make an airplane fly upside down the pilot must:
D. point the nose of the plane slightly up to create a positive angle of attack on the "wrong" side of the wing
When your house was new the clean copper pipes could deliver a generous flow of water to the shower. A decade later calcium deposits have reduced the inside diameter of the pipes and the shower feels weaker because:
D. the water must flow faster through the smaller opening in the pipe. since it has more kinetic energy it has less available pressure potential energy to drive the shower
The fastest types of racing cars, Formula 1 and Indy cars, have wings attached to them to increase the downward force on their wheels and thus increase traction. The wings generate:
A. both drag and lift
You are floating along in a hot air balloon. You look up and notice that the bottom of the balloon is open. Although there is a minor loss of hot air due to the diffusion of molecules, the majority of the hot air remains inside the balloon despite this opening because
D. the air pressure inside the balloon's opening is the same as the air pressure outside that opening
One of the most effective strokes in tennis is the top spin serve, in which the top of the ball spins away from the player who hit it. Which way is the lift force on this ball directed? (from p201 of your text)
The principal advantage of sending electric power across country on very high voltage transmission lines is that
B. electric power lost in the wires is greatly reduced
It is a warm summer day and you are having lunch outdoors on a patio. A window air conditioning unit hums quietly nearby as it cools an office inside the building. Your friend notices that the unit's outdoor part is emitting a considerable amount of heat and comments on how strange that is. You explain correctly that the air conditioner's outside part is emitting the heat
C. it removes from the inside air and the heat it produces from the electricity it consumes
Household electricity in the USA is
C. 120 volt alternating current
Can an electric current produce a magnetic field?
A. yes, a current always produces a magnetic field
Which of the following is a fundamental unit in the MKS system?
Which of the following is a scalar quantity?
Using precise physics definitions, President Obama has energy when:
A. he is flying in Air Force One
How much momentum do the CNU Captains have when they are gathered for the coach's briefing after they have defeated three consecutive football teams? Assume the CNU team roster includes 45 players with an average mass of 85 kg.
0.0 kg m/s2P=mv
Which of Newton's Laws is most responsible for your professor's ability to jerk a table cloth out from under a full coffee cup without spilling its contents?
A. 1st law (inertia)
Why does a hockey player continue to glide straight ahead even though he is not pumping his legs?
B. he has linear momentum and the force of the ice is small so it takes a long time to produce enough total impulse to transfer this momentum elsewhere
When is your car not accelerating?
C. when you are speeding down a straight stretch of I-64 at 80 mph
Bolts and screws are customarily made following the "right hand rule" for rotary motion. You want to tighten the screw that holds the cover plate on your dorm wall electric outlet. You should:
A. turn it clockwise
It is much more damaging to be hit by a bullet than it is to be hit by the recoiling butt of the gun that fired it because:
A. the bullet has more kinetic energy than the gun
Both heavy and light bowling balls are available at the local lanes. If you push a heavy ball with the same force as a light one with half the heavy ball's mass, how much faster will the light ball accelerate?
D. twice as fast
A 1.6 meter tall marksman can hit a target 1.6 meters high across a 100 meter wide flat field because
B. the gun barrel is pointed slightly upward to compensate for the inevitable effect of gravity
The antilock brake system in modern cars momentarily turns off braking power to individual wheels when the control system senses that a skid is imminent. Why does interrupting the braking force at a critical moment actually decrease the distance required to stop the car?
A. by momentarily reducing the brake force the system maintains static friction and sustains a greater force between the individual tire and the road
A force of 12N is required to pull a 4 Kg block across a level floor (which is NOT frictionless) to the right at a constant velocity. What is the magnitude of the frictional force?
When cutting cardboard with scissors, why is it a good idea to move the cardboard as close as possibly to the scissors' pivot point?
C. there is a constant torque, so a small lever arm gives a large force
You are trying to remove a stuck nut from a bolt. The bolt is in the vertical direction, so to remove the nut you get a wrench which will be turning in the horizontal plane. You realize that to be successful you must maximize the torque. Which of the following techniques will help you maximize the torque?
D. all of the above will help maximize the torque
When the springboard diver performs a multiple spin dive she:
B. tucks her body to reduce her moment of inertia
You are riding the decrepit elevator down from the second floor of Gosnold Hall to ground level. When the door closes the old machine lurches downward. What is true at that moment?
A. your mass and your instantaneous weight both remain the same
When we did the "shoot the professor" demo, why did the paintball stop without breaking?
C. by wearing the fluffy coats the professor maximized the time over which the force is applied to the paintball, and therefore he minimized the force which was applied
You want to position a bird feeder on a tree limb outside your window. However, the further you shinny out on the horizontal branch the risk that you will break the limb off the tree at the point it joins the trunk increases. Why?
B. your torque on the junction between the limb and the trunk increases as you move further out
The handicap access ramp on a building near CNU takes a long route down the side of the building and even makes a right turn around the back before it reaches the pavement. Why didn't the builders make a shorter ramp without the awkward turn?
B. the longer ramp requires less force on the wheelchair to acquire the gravitational potential energy of the elevated porch
What part of your car can cause it to change its velocity without changing its speech?
C. the steering wheel
When the total energy of a soccer ball includes both kinetic and potential energy you can be sure it is:
C. moving in some direction and in an elevated position
Based on our class discuss, we know that high quality hold jewelry will be:
C. denser (more mass/volume) than a cheaper alloy
Although a perfectly smooth golf ball (without aerodynamic dimples) will have a terribly short range its reduced lift will offer what advantage to an amateur player?
B. reduced sideways curving flight ("slice")
When one of the F-22 Raptor fighters as Langley AFB launches a rocket powered weapon, what does the missile push against to accelerate away from the airplane?
D. its own exhaust (3rd law)
Doubling the flow velocity in a water pipe will increase the kinetic energy of the stream by what factor?
D. four times
An astronaut is in orbit in the International Space Station. Which of the following statements is true?
C. the astronaut feels weightless because both she and the station are accelerating at the same rate
A curve ball pitch in baseball curves because of
C. lift forces
Archimedes principle states that the buoyant force exerted by a fluid on an object wholly or partially immersed in it is equal to
C. the weight of the fluid displaced by the object
Which fundamental law of physics provides the primary basis for Bernoulli's principle that pressure and velocity can be exchanged in a flowing fluid?
D. conservation of energy
Why does tennis ball not slow down very quickly when hit?
C. the fuzz causes turbulence that energizes the boundary layer of air
The driver of a ski boat can feel the effect of the skier's antics. When the skier turns hard to the left or right, the boat slows down slightly because:
C. the skier increased his drag when he generated the lift needed to accelerate him from side to side
Pure turbo jet engines are fuel hogs compared to propellers because:
D. the jet imparts a bigger velocity change to a smaller mass flow of air to generate thrust
The magnitude of the gravitational force that the earth exerts on the moon is ________ the magnitude of the force that the moon exerts on the earth?
C. the same as
Why does the front edge of a Boeing 737's wing have a row of very small metal fins sticking straight up from the otherwise smooth surface? Think about sports balls.
A. to energize slow moving the boundary layer and delay flow separation from the wing
Physics terms are often incorrectly used in the popular press. Identify the error in this statement from the Discovery Channel: "Dirty Jobs" hero Mike Rowe is afraid of a shark that can bite with a force of 2000 pounds per square inch.
A. bite force should be specified in pounds, not pounds per square inch
Which of these men was NOT involved in the discovery of the motions of the planets?
Noise canceling headphones widely advertised by Bose make an airplane ride seem quieter by producing additional sounds that:
C. destructively interfere
A child swinging on a playground swing set travels back and forth at a steady rate. What determines the period of the child's motion?
B. the strength of earth's gravity and the length of the chains
The foam "peanuts" commonly used for packing acquire a negative charge when they are emptied out the shipping container. The pesky things are hard to get rid of and insist on clinging to your arms because:
D. the peanut charge polarizes the surface of your body and draws your positive charges near it
Fast food joints keep their French fries under lamps that just have a slight reddish glow. These apparently feeble bulbs keep the food warm by:
C. radiation. the lamps emit mostly invisible infrared light. these electromagnetic waves are absorbed by the fries and transfer heat to them
You are standing on a plastic bench that insulates you from your surroundings. Both you and the helium balloon you are holding are electrically neutral. You now rub the balloon against your sweater, so that the balloon becomes negatively charged, and then you let the balloon float away. You are left
B. with a positive electric charge
Which of the following quantities is not conserved? a. angular momentum
Polar explorers typically choose light color parkas because:
B. they want to reduce their radiation heat loss by lowering their emissivity
Electromagnetic waves have many characteristics in common with water waves, "Slinky" waves and sound waves. However, one unique feature of the electromagnetic waves that sets them apart is:
D. they can travel through vacuum
If the tires on your car wear unevenly the car may roll smoothly on city streets but it will start to shake as you pick up speed on the highway. The shaking seems to be really annoying at a certain speed but it appears to smooth out if you drive even faster. Why?
A. the suspension of the car has a resonant frequency. when the speed dependent shaking frequency of the lumpy tire hits this frequency the vibration become terrible. at higher and lower speeds the tire vibrations have the wrong period to efficiently drive the resonance
The south pole of a permanent button style magnet will stick to a mild steel refrigerator door. The north pole of the same magnet will stick equally well to the same place on the refrigerator door because:
A. the microscopic domains in the soft steel of the door temporarily align to produce an opposite magnetic pole on the door surface. the opposite poles attract
If you remove only one of the two wires connected to your car battery neither the lights nor the radio will work at all because:
A. removing one wire creates an open circuit for all of the electrical parts of the car
Water waves tend to hit parallel to the beach because of: a. interference among different wavelengths in the complex wave
b. reflection of the previous wave redirects the next one parallel to the shore
c. refraction caused by slowing of the wave as it interacts with the shallows
c. refraction caused by slowing of the wave as it interacts with the shallows
Coulomb's law is similar to the universal law of gravitation in that
D. they are both inverse square laws
Can a magnetic field produce a current?
A. yes, it can produce a current in a loop of wire, but to do so the strength of the magnetic field must change or the orientation of the loop must change
A piano has two or three strings that are struck simultaneously when each individual key is pressed. If these strings are not properly tuned to exactly the same pitch the sound will pulsate (change in intensity) as the key is held down. Why?
A. the sound waves from the strings interfere, alternately destructively and constructively
Why are the insides of thermos bottles typically shiny and metallic looking?
B. the shiny lining has a very low emissivity and keeps the radiation energy loss small
What scientist championed alternating current and transformers as the technology basis of practical electric power distribution?