Read the diagram, identify the mechanical relationship and predict what changes.
Ignoring the weight of the beam, what downward force F balances this lever?
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Ignoring the weight of the beam, what downward force F balances this lever?
Answer: B — 40 N
For balance, the clockwise and counterclockwise moments about the pivot must match. The left moment is 60 N × 2 m = 120 N·m. Therefore F × 3 m = 120 N·m, giving F = 40 N. A longer lever arm needs less force for the same moment.
Open a topic to review the method, then practice applying it to a new question.
Identify the object being considered, then the forces acting on it. Balanced forces mean no acceleration; they do not necessarily mean that the object is stationary.
Friction resists relative sliding or the tendency to slide between surfaces. Distinguish the direction an object moves from the direction of a particular force acting on it.
The turning effect of a force is torque. For a perpendicular force, torque = force × distance from the pivot. More generally, use the perpendicular distance from the pivot to the force’s line of action.
For an ideal balanced lever, clockwise and counterclockwise torques are equal. A longer effort arm reduces the force required, while increasing the distance the effort moves.
A 60 N load acts 0.4 m to one side of a pivot. What perpendicular force 1.2 m on the other side balances it? Ignore the lever’s weight.
Answer: 20 N.
The load torque is 60 × 0.4 = 24 N·m. Balancing requires F × 1.2 = 24, so F = 20 N.
Two external gears in direct contact turn in opposite directions. Their rotational speeds are inversely related to their tooth counts. An intermediate idler can change direction without changing the overall speed ratio between the first and last gear.
In an ideal pulley system, count the rope segments supporting the moving load. More supporting segments can reduce the required effort, but more rope must be pulled. Count support at the moving block, not every visible line.
For a constant force in the direction of movement, work = force × distance. Power is the rate of doing work: power = work ÷ time. Doing the same work faster requires greater average power.
An ideal machine trades force for distance without creating energy. Real machines lose some useful energy through effects such as friction, so their output work is less than their input work.
Pressure = force ÷ area. The same force over a smaller area produces greater pressure. Fluid pressure at a given depth increases with fluid density and depth.
For an ideal enclosed hydraulic system at comparable height, a pressure change is transmitted through the fluid. A larger output piston area can produce a larger force, with a corresponding reduction in travel distance.
An ideal hydraulic system has an input piston area of 2 cm² and an output area of 10 cm². What output force results from a 30 N input force?
Answer: 150 N.
The output area is 5 times larger. With the same transmitted pressure and no losses, the output force is 5 × 30 = 150 N.
Many questions can be solved by identifying a direction or comparison. Know a small set of relationships, then practice choosing which applies. Check pivots, connections, areas and stated assumptions before calculating.
Those assumptions define the model so the answer is unambiguous. Real machines have additional effects; use the assumptions given in the question rather than silently adding or removing them.
Original independent practice. Scores show performance on our questions, not an official ASVAB result.
Read the diagram, identify the mechanical relationship and predict what changes.
4,700+ candidates · 68,000+ practice sessions across Game Assessment Prep.
Ignoring the weight of the beam, what downward force F balances this lever?
This original example is free to use without an account and is separate from the scored practice bank.
Ignoring the weight of the beam, what downward force F balances this lever?
Answer: B — 40 N
For balance, the clockwise and counterclockwise moments about the pivot must match. The left moment is 60 N × 2 m = 120 N·m. Therefore F × 3 m = 120 N·m, giving F = 40 N. A longer lever arm needs less force for the same moment.
Open a topic to review the method, then practice applying it to a new question.
Identify the object being considered, then the forces acting on it. Balanced forces mean no acceleration; they do not necessarily mean that the object is stationary.
Friction resists relative sliding or the tendency to slide between surfaces. Distinguish the direction an object moves from the direction of a particular force acting on it.
The turning effect of a force is torque. For a perpendicular force, torque = force × distance from the pivot. More generally, use the perpendicular distance from the pivot to the force’s line of action.
For an ideal balanced lever, clockwise and counterclockwise torques are equal. A longer effort arm reduces the force required, while increasing the distance the effort moves.
A 60 N load acts 0.4 m to one side of a pivot. What perpendicular force 1.2 m on the other side balances it? Ignore the lever’s weight.
Answer: 20 N.
The load torque is 60 × 0.4 = 24 N·m. Balancing requires F × 1.2 = 24, so F = 20 N.
Two external gears in direct contact turn in opposite directions. Their rotational speeds are inversely related to their tooth counts. An intermediate idler can change direction without changing the overall speed ratio between the first and last gear.
In an ideal pulley system, count the rope segments supporting the moving load. More supporting segments can reduce the required effort, but more rope must be pulled. Count support at the moving block, not every visible line.
For a constant force in the direction of movement, work = force × distance. Power is the rate of doing work: power = work ÷ time. Doing the same work faster requires greater average power.
An ideal machine trades force for distance without creating energy. Real machines lose some useful energy through effects such as friction, so their output work is less than their input work.
Pressure = force ÷ area. The same force over a smaller area produces greater pressure. Fluid pressure at a given depth increases with fluid density and depth.
For an ideal enclosed hydraulic system at comparable height, a pressure change is transmitted through the fluid. A larger output piston area can produce a larger force, with a corresponding reduction in travel distance.
An ideal hydraulic system has an input piston area of 2 cm² and an output area of 10 cm². What output force results from a 30 N input force?
Answer: 150 N.
The output area is 5 times larger. With the same transmitted pressure and no losses, the output force is 5 × 30 = 150 N.
Many questions can be solved by identifying a direction or comparison. Know a small set of relationships, then practice choosing which applies. Check pivots, connections, areas and stated assumptions before calculating.
Those assumptions define the model so the answer is unambiguous. Real machines have additional effects; use the assumptions given in the question rather than silently adding or removing them.
Original independent practice. Scores show performance on our questions, not an official ASVAB result.