Mechanical Comprehension · Practice test 4

Question 1Not answered

A wedge is best described as

1. an inclined plane that moves
2. a lever with a very short arm
3. a wheel and axle without the wheel
4. two pulleys working in opposition

Question 2Not answered

The difference between an object's mass and its weight is that weight

1. is the force gravity exerts on that mass
2. is the amount of matter the object contains
3. is the same everywhere in the universe
4. is measured in kilograms rather than newtons

Question 3Not answered

A single fixed pulley attached to a ceiling changes the direction of a pulling force but its mechanical advantage is

1. 2
2. 1
3. 0.5
4. it has no mechanical advantage number

Question 4Not answered

A pump rated at 2 horsepower runs for 10 seconds. Roughly how much energy, in joules, does it deliver? Use 746 watts per horsepower.

1. about 14,920 joules
2. about 7,460 joules
3. about 746 joules
4. about 149,200 joules

Question 5Not answered

A belt running between two pulleys in a crossed figure-eight makes them turn

1. in the same direction
2. at exactly the same speed
3. in opposite directions
4. with the larger one going faster

Question 6Not answered

An idler gear placed between a driver and a driven gear

1. increases the overall gear ratio of the train
2. reduces the torque delivered to the output
3. reverses the output direction without changing the ratio
4. keeps the two gears turning at different speeds

Question 7Not answered

An astronaut's mass is 80 kilograms on Earth. What is her mass on the Moon?

1. about 13 kilograms
2. 80 kilograms
3. about 480 kilograms
4. 0 kilograms, she is weightless

Question 8Not answered

A gear train has three gears meshed in a row: A drives B, and B drives C. If gear A turns clockwise, which direction does gear C turn?

1. counterclockwise
2. gear C does not move
3. clockwise
4. it depends only on gear C's own size

Question 9Not answered

In a block and tackle with an ideal mechanical advantage of 6, what is the trade-off for the reduced effort needed to lift a load?

1. the effort rope must be pulled 6 times farther than the load rises
2. the load rises 6 times faster than the rope is pulled
3. there is no trade-off, the system is a free gain
4. the rope must be exactly 6 metres long

Question 10Not answered

A picture frame hangs motionless from a single nail. What can be said about the forces acting on it?

1. the frame has no weight
2. they are balanced, summing to zero
3. the nail exerts no force on the frame
4. gravity has been cancelled out entirely

Question 11Not answered

A beam rests on two supports and a load is placed close to one end. That support will carry

1. more of the load than the far support
2. less of the load than the far support
3. exactly half of the load
4. none of the load at all

Question 12Not answered

Moving a lever's fulcrum closer to the load will

1. decrease the mechanical advantage
2. increase the mechanical advantage
3. leave the mechanical advantage unchanged
4. reverse the direction of the output force

Question 13Not answered

A pulley system with a mechanical advantage of 3 is used to lift 150 pounds. What effort is required, ignoring friction?

1. 450 pounds
2. 75 pounds
3. 147 pounds
4. 50 pounds

Question 14Not answered

A rotating shaft supported by ball bearings, compared to the same shaft resting directly in a plain metal sleeve, will generally experience

1. more friction
2. exactly the same friction
3. no friction at all under any load
4. less friction, since rolling resistance is lower than sliding friction

Question 15Not answered

A hydraulic system has a small piston with area 5 square centimetres and a large piston with area 50 square centimetres. If a force of 20 newtons is applied to the small piston, what force does the large piston produce?

1. 2 newtons
2. 200 newtons
3. 20 newtons
4. 100 newtons

Question 16Not answered

Triangular bracing is commonly used in trusses and towers because a triangle, unlike a plain rectangle,

1. uses less material than any other shape regardless of load
2. cannot change shape without one of its sides changing length
3. is easier to manufacture than a rectangle
4. only works when made from steel

Question 17Not answered

Compared to a first-class lever with the fulcrum exactly in the middle, a third-class lever such as a broom always has a mechanical advantage that is

1. less than 1
2. greater than 1
3. exactly equal to 1
4. undefined, since third-class levers have no load arm

Question 18Not answered

In a train of three meshed gears, the first and the last turn

1. in opposite directions
2. at the same speed always
3. in the same direction
4. in directions that depend on their sizes

Question 19Not answered

A ball dropped from a cliff, ignoring air resistance, gains speed at a rate of about

1. a constant 9.8 metres per second, unchanging
2. 9.8 metres every second squared, decreasing over time
3. zero, since only mass affects fall speed
4. 9.8 metres per second every second

Question 20Not answered

Water flows through a wide section of pipe into a much narrower section. Compared to the wide section, the water's speed in the narrow section is

1. faster
2. slower
3. exactly the same
4. zero, since the pipe narrows

Question 21Not answered

A crate weighing 100 pounds on Earth is taken to the Moon. On the Moon it will have

1. less mass and less weight
2. the same mass but less weight
3. the same mass and the same weight
4. more mass but the same weight

Question 22Not answered

A lever has a load arm of 3 metres and needs a mechanical advantage of 5. How long must the effort arm be?

1. 1.7 metres
2. 8 metres
3. 5 metres
4. 15 metres

Question 23Not answered

An object moving in a circle is held on its path by a force directed

1. outward, away from the centre
2. forward, along the direction of travel
3. toward the centre of the circle
4. backward, opposing the motion

Question 24Not answered

A hammer and a feather are dropped together on the Moon, where there is no air. Which hits the ground first?

1. the hammer, because it is heavier
2. the feather, because it is lighter
3. they land at the same time
4. neither lands, since there is no gravity on the Moon

Question 25Not answered

A wheelbarrow is an example of which class of lever?

1. First class
2. Third class
3. Fourth class
4. Second class