physics 101 test 2 practice exam

You stop for a cappuccino at a coffee shop and notice that the tiny white bubbles of steamed milk remain on the surface of the coffee. These air-filled bubbles stay where they are, rather than descending into the coffee or rising into the air, because they are A. less dense than the coffee but more dense than the air above the coffee. B. more dense than the coffee but less dense than the air above the coffee. C. lighter than the cup of coffeebut heavier than the column of air above the coffee.

A. less dense than the coffee but more dense than the air above the coffee.

The top surface of a calm, smoothly flowing stream is always at atmospheric pressure. As water in this stream runs into a tree stump and slows almost to a stop, the water's top surface A. shifts upward slightly above the normal stream level. B. shifts downward slightly below the normal stream level. C.stays at the same height and does not begin to rotate. D. stays at the same height but begins to rotate clockwise as viewed from above.

A. shifts upward slightly above the normal stream level.

A squirt gun is a simple type of water pump in which a plunger attached to the trigger forces water out of a nozzle and across the room. When you squeeze the trigger of the gun, water squirts out of the nozzle because A. the pressure inside the gun is higher than atmospheric pressure. B.the water is compressed at the plunger so it must expand out the nozzle. C.the Bernoulli effect causes the pressure of water leaving the nozzle to be less than atmospheric pressure. D.the Bernoulli effect causes the water's overall energy to increase as it travels through the narrow nozzle.

A. the pressure inside the gun is higher than atmospheric pressure.

For an object that sinks in a fluid, A. the weight of fluid displaced is less than its weight. B. the weight of the fluid displaced is greater than the object's weight. C. the weight of the fluid displaced equals the object's weight. D. the weight of the object becomes more than in air.

A. the weight of fluid displaced is less than its weight.

When you pour honey into a bowl, it flows smoothly. If you did the same with water, it would splash. These different behaviors occur because honey's high A. viscosity keeps it flowing smoothly while water's low viscosity allows inertia to break its flow into many separate pieces. B.momentum keeps it moving in a straight line while water's low momentum allows it to turn abruptly in many different directions. C.density keeps it flowing smoothly while water's low density allows it to float upward and splash about. D.mass keeps it flowing smoothly while water's low mass allows it to acquire lots of angular momentum.

A. viscosity keeps it flowing smoothly while water's low viscosity allows inertia to break its flow into many separate pieces.

The rest energy of a 60 kg person is: A. 8.4x10^18J B. 5.4x10^18J C. 1.8x10^10J D. 9x10^16J

B. 5.4x10^18J

Suppose you are operating a fan and it is stalling. One thing that would not prevent stalling would be to A. slow down the fan. B. speed up the fan.

B. speed up the fan.

A top is A. statically stable and dynamically unstable. B. statically unstable and dynamically stable. C. statically unstable and dynamically unstable. D. statically stable and dynamically stable.

B. statically unstable and dynamically stable.

The onset of turbulent flow happens for a Reynolds number of about A. 0 B. 530 C. 2300

C. 2300

Why does fuzz on a tennis ball help it travel farther when hit? A. The fuzz causes turbulence on the leading edge of the ball only. B. The fuzz causes turbulence on the trailing edge of the ball only. C. The fuzz "trips" the boundary layer, causing turbulence everywhere around the ball. D. The fuzz causes laminar flow everywhere.

C. The fuzz "trips" the boundary layer, causing turbulence everywhere around the ball.

At various times in the news it has been reported that certain vehicles are susceptible to rolling over. The physical mechanism that is responsible for rollovers is A. frictional torques about the driver only. B. frictional torques from the vehicle on the road acting below the road's center of mass. C. frictional torques from the road on the vehicle about its center of mass, which is below the rider. D.strong air currents simply blowing the system over.

C. frictional torques from the road on the vehicle about its center of mass, which is below the rider.

The speed at which a car must move so that its relativistic energy is three times its rest energy is A. 1/9 times the speed of light. B. 1/3 times the speed of light. C. √(8/9)times the speed of light. D. 8/9 times the speed of light.

C. √(8/9)times the speed of light.

You are holding two identical-looking balloons, one filled with air and one filled with water. You drop these two balloons from a very tall bridge and notice that the water-filled balloon hits the ground first because its terminal velocity is larger. The terminal velocity of the water balloon is larger than that of air balloon because A. conservation of momentum requires the lighter air-filled balloon to travel more slowly. B. although the drag forces on the two equally shaped balloons are the same, the buoyant force on the air balloon is larger so the net force on that balloon is smaller and it falls more slowly. C.the larger force of gravity on the water balloon must be balanced by a larger drag force, which occurs at a higher speed. D.although the force of gravity on the two balloons is the same, the water balloon has more inertia and travels downward more quickly.

C.the larger force of gravity on the water balloon must be balanced by a larger drag force, which occurs at a higher speed.

The reason fast-moving water makes noise is A. vortices. B. chaos. C. laminar flow. D. turbulence.

D. turbulence.

Water weighs about 10 N per liter. A 4.0 liter ball is pushed underwater. What is the buoyant force on the ball? A. 4.0 liters B. 10 N C. 20N D.40 N

D.40 N