A person lifts a 3.8 kg cement block a vertical distance 0.9 m and then carries the block horizontally a distance 7.3 m. Determine the work done by the person and by the force of gravity in this process.
? J (by person)
? J (by force of gravity)
work done on gravity= mass*g*heightlifted.
work done by gravity= -mgh
i don't understand
To determine the work done by the person, we can use the formula:
Work = Force * Distance
Firstly, we need to calculate the force exerted by the person to lift the cement block. We can do this using the formula:
Force = Mass * Acceleration due to gravity
The mass of the cement block is given as 3.8 kg, and the acceleration due to gravity is approximately 9.8 m/s^2.
Therefore, the force exerted by the person to lift the cement block is:
Force = 3.8 kg * 9.8 m/s^2 = 37.24 N
Next, we can calculate the work done by the person to lift the cement block vertically a distance of 0.9 m. The formula for work is:
Work = Force * Distance
Substituting the values we have:
Work = 37.24 N * 0.9 m
Work = 33.516 J (rounded to three decimal places)
Therefore, the work done by the person is approximately 33.516 Joules.
To determine the work done by the force of gravity, we can use the formula:
Work = Force * Distance
The force of gravity is acting vertically downwards, so the angle between the force and distance is 180 degrees. Therefore, the work done by the force of gravity is:
Work = Force * Distance * cosθ
In this case, the force of gravity is equal to the weight of the cement block, which is:
Force = Mass * Acceleration due to gravity
Substituting the given values:
Force = 3.8 kg * 9.8 m/s^2
Force = 37.24 N
The distance over which the force of gravity acts is the vertical distance the cement block is lifted, which is 0.9 m.
Finally, using the formula for work:
Work = 37.24 N * 0.9 m * cos 180°
Since cos 180° = -1, we can simplify the equation:
Work = 37.24 N * 0.9 m * -1
Work = - 33.516 J (rounded to three decimal places)
Therefore, the work done by the force of gravity is approximately -33.516 Joules. The negative sign indicates that the force of gravity opposes the displacement of the cement block.