Physics
Forces, Energy and Machines
267 Questions
Forces, energy, and machines are fundamental physics concepts focusing on mechanics, work, power, and simple machines. These topics regularly appear in general science sections of competitive exams. Use these questions to practice calculating resultant forces, mechanical advantage, and work done in various scenarios.
Resultant force calculationsMechanical advantage of leversWork and power equationsApparent weight in elevatorsBending moments
Forces, Energy and Machines Questions
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lifting a couch from the ground into a truck
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carrying a chair upstairs to a house
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wheeling a dresser up a ramp into a house
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lifting a box from the floor onto a shelf.
C
Correct answer
Explanation
Using a ramp (an inclined plane) allows you to move an object to a higher elevation using less force than lifting it vertically, because the distance is increased.
B
Correct answer
Explanation
The principle of simple machines involves a trade-off: you can use less force, but you must apply that force over a longer distance to perform the same amount of work.
A
Correct answer
Explanation
A movable pulley is attached to the load itself. It allows the user to lift a load with less force, though it does not change the direction of the pull.
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kinetic energy
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potential energy
A
Correct answer
Explanation
Kinetic energy is the energy an object possesses due to its motion.
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kinetic energy
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potential energy
B
Correct answer
Explanation
Potential energy is stored energy based on an object's position or configuration, such as height above the ground.
D
Correct answer
Explanation
Pressure is calculated as force divided by area (P = F/A). Here, 200N / 10m^2 = 20 Pa.
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200 ft / 21 m
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250 ft / 76 m
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300 ft / 91 m
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325 ft / 99 m
D
Correct answer
Explanation
Gravitational potential energy is calculated as PE = mgh. Since mass and gravity are constant, the potential energy is greatest at the highest point.
D
Correct answer
Explanation
Work is calculated as force multiplied by distance. Given a force of 10N and a distance of 50m, the work done is 10N * 50m = 500 Joules.
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1 Joule
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5 Joules
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7 Joules
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10 Joules
A
Correct answer
Explanation
Lifting a small object like an apple (weighing roughly 1 Newton) by a distance of about 1 meter requires approximately 1 Joule of work. The other options represent significantly higher amounts of energy.
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work = distance x area
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work = force x distance
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distance = work x force
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force = speed x distance
B
Correct answer
Explanation
The scientific definition of work is the product of the force applied to an object and the distance the object moves in the direction of that force (W = F * d).
A
Correct answer
Explanation
Non-moving objects at a height possess gravitational potential energy due to their position relative to the ground. This stored energy has the potential to do work when the object is released and begins to fall.
A
Correct answer
Explanation
Mechanical energy is defined as the sum of kinetic energy (energy of motion) and potential energy (stored energy of position). Therefore, it can exist in either or both of these forms.
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23 N to the left (-x)
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23 N to the right (+x)
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17 N to the left (-x)
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17 N to the right (+x)
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Rise/Run
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Run/Rise
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Rise + Run
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Rise x Run
A
Correct answer
Explanation
Slope is defined as the change in the vertical direction (rise) divided by the change in the horizontal direction (run).
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work
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stress
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power
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efficiency
A
Correct answer
Explanation
Work done is defined as the product of the force applied and the distance moved in the direction of the force.