Middle School

You carry a 5 kg sack of potatoes across the store for 5 minutes and wait in line holding it for 30 seconds before you get tired and drop it. You then lift the sack of potatoes upwards for 160 cm and place it on the counter. How much work did you do at the store?

Answer :

Answer:

The only work done is when the person lifts the sack over a distance, W = 78.48 [N]

Explanation:

We have to remember the definition of work, which tells us that work is the result of a force by a distance, we must apply this concept in each of the movements of the person in the problem described.

W = F * d

where:

F = force [N]

d = distance [m]

The force is given by the producto of the mass by the gravity.

F = 5 * 9.81 = 49.05 [N]

W = 49.05 * 1.6 = 78.48 [N]

To calculate the work done in lifting a 5 kg sack of potatoes 1.60 meters onto the counter, the force due to gravity (about 49 N) is multiplied by the distance (1.60 m) to find that 78.4 Joules of work was done.

The question asks how much work was done by a person while carrying and lifting a sack of potatoes in a store. To answer this, we can use the physics concept that work is done when a force causes a displacement. Carrying the bag horizontally doesn't require work against gravity (unless you change your speed or direction), but lifting it upwards does. When the sack is lifted upwards for 1.60 meters (160 centimeters), the weight of the potatoes (5 kg) experiences a force due to gravity (weight = mass imes gravity, which is approximately 5 kg imes 9.8 m/s2 = 49 N). The work done is then calculated as Work = Force imes Distance, which is 49 N imes 1.60 m = 78.4 Joules of work done to put the sack on the counter.

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