A person lifts a 4.3 kg cement block a vertical
distance of 1.3 m and then carries the block
horizontally a distance of 5.3 m.
The acceleration of gravity is 9.81 m/s
2
.
a) Determine the work done by the person
in the process.
Answer in units of J
YOlO
To determine the work done by the person, we can use the formula:
Work = Force x Distance x cos(theta)
Where:
- Force is the force exerted by the person to lift the cement block, which is equal to the weight of the block.
- Distance is the distance over which the person lifts the block vertically.
- Theta is the angle between the force and the direction of motion.
To calculate the force, we'll need to find the weight of the block, which can be determined using the formula:
Weight = mass x acceleration due to gravity
Given:
- mass = 4.3 kg
- acceleration due to gravity = 9.81 m/s^2
Weight = 4.3 kg x 9.81 m/s^2
Weight = 42.183 kg⋅m/s^2 (approximately)
Now, we can calculate the work done by the person lifting the cement block. Since the block is lifted vertically, the angle between the force and the direction of motion is 0 degrees (cosine of 0 degrees is 1).
Work = 42.183 kg⋅m/s^2 x 1.3 m x cos(0)
Work = 42.183 kg⋅m^2/s^2
Finally, we need to convert the units to joules (J). Since 1 J equals to 1 kg⋅m^2/s^2, the work done is equal to:
Work = 42.183 J (approximately)
Therefore, the work done by the person in lifting the cement block vertically is approximately 42.183 joules (J).
There is no work done by moving the load horizontally.
The only work done is the lifting, which is equivalent to the potential energy gained by the block given by:
Ep=mgh.