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WorksheetsActivity 1.2.5 Mechanical System Efficiency
Total questions: 17
Worksheet time: 22mins
Lamar Gant, U.S. powerlifting star, became the first man to deadlift five times his own body weight in 1985. Deadlifting involves raising a loaded barbell from the floor to the level of the hips with outstretched arms. Determine the work done by Lamar in deadlifting 300 kg to a height of 0.90 m above the ground (W=Fd).
270 J
2646 J
333 J
3.00X10-3 J
45 J of work were done on the object that moved 5 meters. How much force was applied to the object?
8 N
225 N
9 N
0 N
Wind turbines and hydroelectric energy make electricity by converting what type of energy into electrical energy?
chemical
mechanical
heat
nuclear
The law of energy conservation says the total energy before a process _______ the total energy after it
is less than
is more than
affects
equals
Energy Efficiency is calculated by useful energy (Energy Out) divided by energy consumed (Energy In) , expressed as a percentage
False
True
What is the efficiency of the machine if the input (energy consumed) is 263 J and the output (useful energy) is 142 J?
6.26%
54%
100%
260%
How much energy is wasted by a machine if the energy consumed (input) is 263 J and the useful energy (output) is 142 J?
405 J
395 J
121 J
1.85 J
The SI unit of power is...
British thermal unit (BTU)
horsepower
joules
watts
Work is done when
a force acts on an object.
a force acts on an object and the object moves in the same direction.
the mass of an object changes.
the velocity of an object changes.
In the International System of Units (SI) forces are measured in _____________, and distances/length are measured in ________________.
pounds, miles
ounces, feet
newtons, meters
joules, meters
A man holds a heavy package for one hour.
Work
No Work
A boy lifts a heavy package.
Work
No Work
