Q:

# How much force do you exert when you lift a 50-pound dumbbell?

A:

A 50 pound-mass dumbbell is pulled downward by the Earth's gravitational field at an acceleration of 32.174 feet-pound-mass per second squared, so the force to lift it is 1,608.7 pounds-force. Newton's second law of motion states that force is equal to mass multiplied by acceleration, gravitational or otherwise.

## Keep Learning

A pound-mass needs to be distinguished from pound-force because they are not equivalent units. A pound-mass refers to how much mass an object possesses; in the case of the dumbbell, it is a 50-pound-mass object. A pound-force is the unit of force that an object is acted upon. In the example given, lifting a 50-pound-mass weight requires 1,608.7 pounds-force away from the surface of the Earth.

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## Related Questions

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The law of acceleration is formally referred to as Newton's Second Law of Motion and defines the rate of acceleration as a product of the force exerted on the object and the mass of the object. The rate of acceleration increases as the net force increases. The inverse is true for mass, with the acceleration decreasing as the mass increases.

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The concept of air resistance is related to Newton's second law of motion, which describes acceleration and force. Air resistance is a significant factor in how fast an object falls, according to this law.

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For an object with unchanging mass, force equals mass times acceleration. This is abbreviated as f = ma. Force is a push/pull on an object resulting from interactions with another object. Having a magnitude and a direction makes force a vector quantity.