Mechanical Comprehension · Practice test 1

Question 1Not answered

A block requires 50 newtons of force to just begin sliding, but only 35 newtons to keep it sliding at constant speed. The 35 newton force is best described as

1. kinetic friction
2. static friction
3. normal force
4. gravitational force

Question 2Not answered

An air compressor reduces the volume of a fixed amount of gas in a sealed tank. According to this relationship, the gas's pressure will generally

1. increase, since pressure and volume are inversely related at constant temperature
2. decrease
3. stay exactly the same
4. drop to zero

Question 3Not answered

A vertical column holding up a roof is primarily under

1. tension
2. shear
3. compression
4. torsion

Question 4Not answered

The elasticity of a material describes its ability to

1. stretch a long way before it breaks
2. resist being scratched or dented
3. carry a heavy load without bending
4. return to its original shape after being deformed

Question 5Not answered

A screw with a fine thread, many turns per inch, compared to one with a coarse thread requires

1. more force to turn and fewer turns
2. the same force and same number of turns
3. no force at all to turn
4. less force to turn but more turns to drive it the same distance

Question 6Not answered

An air compressor stores energy by

1. squeezing air into a tank at high pressure
2. cooling the air until it becomes liquid
3. charging a battery from the motor
4. raising a heavy weight inside the tank

Question 7Not answered

A brittle material is one that

1. bends a long way before it finally fails
2. breaks suddenly with little bending first
3. is always weaker than a ductile material
4. cannot be scratched by anything harder

Question 8Not answered

In a real pulley system, the effort actually needed is

1. a little less than the ideal calculation predicts
2. exactly what the ideal calculation predicts
3. unrelated to the number of supporting ropes
4. a little more than the ideal calculation predicts

Question 9Not answered

A gear train has a drive gear, an idler gear, and a driven gear, all meshed in sequence. Does the idler gear change the overall gear ratio between the drive and driven gears?

1. yes, it always doubles the ratio
2. yes, it always halves the ratio
3. yes, but only if the idler is the largest gear
4. no, only the number of direction reversals changes

Question 10Not answered

A doorknob has a knob radius of 3 centimetres and a spindle radius of 1 centimetre. How much easier is it to turn the spindle using the knob compared to gripping the spindle directly?

1. about 3 times easier
2. about 1 time easier, no benefit
3. about 9 times easier
4. about 0.3 times, it is harder

Question 11Not answered

On a first-class lever, the fulcrum is positioned

1. at the same point as the load
2. beyond the load, away from the effort
3. beyond the effort, away from the load
4. between the effort and the load

Question 12Not answered

How much work is done raising a 200 pound load 5 feet?

1. 205 foot-pounds
2. 40 foot-pounds
3. 195 foot-pounds
4. 1000 foot-pounds

Question 13Not answered

A swinging pendulum at the very top of its arc has

1. maximum kinetic energy and minimum potential energy
2. maximum potential energy and minimum kinetic energy
3. maximum amounts of both kinds of energy
4. minimum amounts of both kinds of energy

Question 14Not answered

Which generally requires more force to overcome: the static friction to start an object sliding, or the kinetic friction to keep it sliding once moving?

1. kinetic friction is usually greater
2. static friction is usually greater
3. they are always exactly equal
4. neither exists once the object is moving

Question 15Not answered

A gear train increases the driven gear's speed compared to the drive gear. What happens to the torque delivered to the driven gear?

1. torque increases
2. torque stays exactly the same
3. torque decreases
4. torque becomes zero

Question 16Not answered

A pair of fishing rod, where the hand grips near the fixed end and the effort is applied closer to the fulcrum than the far-off catch, is an example of which lever class?

1. first class
2. second class
3. it is not a lever at all
4. third class

Question 17Not answered

A worker holds a heavy box perfectly still at chest height for two minutes. In the physics sense, the work done on the box is

1. zero, because the box does not move
2. equal to the weight times the time held
3. equal to the weight times the chest height
4. greater the longer the box is held up

Question 18Not answered

A drive pulley with a 6 inch diameter is connected by a belt to a driven pulley with an 18 inch diameter. If the drive pulley spins at 300 rpm, how fast does the driven pulley spin?

1. 100 rpm
2. 900 rpm
3. 300 rpm
4. 54 rpm

Question 19Not answered

A flagpole uses a single fixed pulley at the top. Compared to lifting the flag by hand with no pulley at all, pulling the rope down

1. requires half the force
2. requires double the force
3. requires the same force but is more convenient because you pull downward
4. makes the flag rise twice as fast

Question 20Not answered

A nutcracker is an example of which class of lever?

1. First class
2. Third class
3. Second class
4. It is a wedge, not a lever

Question 21Not answered

A 60 pound weight sits 2 feet from a fulcrum. What downward force applied 6 feet from the fulcrum on the other side will balance it?

1. 20 pounds
2. 180 pounds
3. 30 pounds
4. 120 pounds

Question 22Not answered

A nutcracker, hinged at one end with the nut placed between the arms and the hand squeezing near the far end, is an example of which lever class?

1. first class
2. third class
3. second class
4. fourth class

Question 23Not answered

A beam supported at both ends carries a load at its centre. The bending stress is greatest

1. at both of the supported ends
2. at the middle of the beam
3. evenly along the whole beam
4. a quarter of the way along it

Question 24Not answered

A 4 kilogram object moving at 5 metres per second has how much kinetic energy?

1. 50 joules
2. 20 joules
3. 100 joules
4. 10 joules

Question 25Not answered

Compared with the friction of an object already sliding, the friction that must be overcome to start it moving is usually

1. smaller
2. exactly the same
3. greater
4. zero