Question

Awanita is placing items on a shelf that is 200 cm above the ground. She exerts a force of 20 N to lift a box from the floor to the shelf. She does this in 5 s. What is Awanita’s power output? (Power: P = W/t) 4 W 8 W 40 W 800 W.

Answer 1

Hi there!

Begin by calculating the total work done on the object.

Recall:

$\large\boxed{W = \text{ F x d}}$

W = Work (J)

F = Net force (N)

d = displacement (m ⇒ must be parallel to direction of force for this equation to hold. Elsewise, W = Fdcosθ).

We can plug in the given displacement and force. Remember to convert 'cm to 'm'.

$W = 20 * 2= 40 J$

Now, use the following relationship for power:

$\large\boxed{W = Pt, P = \frac{W}{t}}$

Plug in the values:

$P = \frac{40}{5} = \boxed{ 8 \text{Nm/s}}$

Answer 2

The required power output to lift the items on the shelf is of 8 W.

Power:

The power associated with the applied force is defined as the rate of doing work on an object.

Given data:

The vertical distance above the ground is, h = 200 cm = 2 m.

The magnitude of force required to lift the box is, F = 20 N.

The time interval for the lifting is, t = 5 s.

The mathematical expression for the Power is,

P = W/t

here, W is the magnitude of work done.  And its value is, W = F × h

Solving as,

P = F × h /t

P = 20 × 2 / 5

P = 8 W

Thus, we can conclude that the required power output to lift the items on the shelf is of 8 W.

Learn more about the power output here:

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