A student tries to lift up a 100lb rock. At the end of five minutes the rock hasn't moved. How much work (e=fxd) was done on the rock
Work (W) is defined as the force (F) applied on an object multiplied by the distance (d) the object moves in the direction of the force. In this case, the rock did not move, so the distance it moved (d) is zero. Therefore, the work done on the rock is zero.
To calculate the work done on the rock, we will use the formula:
work = force x distance
In this case, the force exerted by the student is equal to the weight of the rock, which is 100 pounds. However, since the rock hasn't moved, there is no displacement or distance over which the force is applied. Therefore, the work done on the rock is zero.
So, no work was done on the rock since it hasn't moved.
To calculate the work done on the rock, we need to determine the force applied and the distance over which the force was applied.
In this case, we are given the weight of the rock as 100 pounds. Weight is actually a force, so it represents the force exerted by the rock due to gravity.
The formula for work is given as W = F * d, where W is the work done, F is the force, and d is the distance covered.
Since the force exerted by the student is equal to the weight of the rock, which is 100 pounds, we can substitute F = 100 pounds.
However, since the rock did not move, the distance covered is zero, or d = 0.
So, the work done (W) on the rock would be W = F * d = 100 pounds * 0 = 0.
Therefore, no work was done on the rock since it did not move.
If it took him 2 seconds to lift the rock, how much power (p=E/t) was needed?
Power (P) is defined as the work (W) done per unit time (t). It is calculated using the formula:
Power = Work/Time
In this case, we just established that no work (W) was done on the rock since it did not move. Therefore, the work done is zero.
The time taken to lift the rock is given as 2 seconds, so we can substitute t = 2 seconds into the formula.
Power = 0 / 2 seconds = 0 watts
Therefore, no power was needed to lift the rock since no work was done on it.
Later his other brother lifts the rock to a height of 6 ft. How much work was done?
To calculate the work done in lifting the rock to a height of 6 feet, we need to know the force applied and the distance over which the force was applied.
The work done (W) is calculated using the formula:
W = F * d
where F is the force applied and d is the distance covered.
In this case, the force applied will still be equal to the weight of the rock, which is 100 pounds.
The distance covered is the height to which the rock was lifted, which is 6 feet.
So, we can substitute F = 100 pounds and d = 6 feet into the formula:
W = 100 pounds * 6 feet = 600 foot-pounds
Therefore, the work done in lifting the rock to a height of 6 feet is 600 foot-pounds.
How many horsepower were used? (550 ft-lbs/sec=1 HP)
To determine the horsepower used, we need to convert the work done in foot-pounds to horsepower.
1 horsepower is equal to 550 foot-pounds per second.
Given that the work done in lifting the rock is 600 foot-pounds, we can divide it by 550 to get the equivalent horsepower:
600 foot-pounds / 550 foot-pounds per second = 1.09 horsepower
Therefore, approximately 1.09 horsepower were used to lift the rock to a height of 6 feet.