Question

URGENT

A skyscraper has lost several of its windows due to stress caused by wind. Each fallen window had a mass of 2.7 kilograms and was originally 64.2 meters above the ground. How much work was done by gravity on each window as it fell to the ground?
Andrea draws this graph to make her calculation. What mistake does Andrea make in her drawing?

She does not take the starting position into account.
She shows a deceasing force.
She reverses the two axes.
She writes the wrong value for force.

Answer 1

1. The work done by gravity on each window as it fell is 1698.732 Joules

2. The mistake Andrea make in her drawing is she wrote the wrong value for force (option E)

How to calculate the work done by gravity and the mistake of Andrea?

1. The work done by gravity on each window as it fell can be calculated as shown below:

• Mass of window (m) = 2.7 Kilograms
• Height from the ground (h) = 64.2 meters
• Acceleration due to gravity (g) = 9.8 m/s²
• Work done by gravity = ?

Work done by gravity = mass × acceleration due to gravity × height

= 2.7 × 9.8 × 64.2

= 1698.732 Joules

2. The mistake Andrea make in her drawing is she wrote the wrong value for force.

If we calculate the force exerted by gravity, we will see that she made mistake in the value of force. This is shown below:

• Mass of window (m) = 2.7 Kilograms
• Acceleration due to gravity (g) = 9.8 m/s²
• Force (F) =?

Force = Mass of object × acceleration of object

= 2.7 × 9.8

= 26.46 N

From the graph shown, Andrea wrote 2.7 N for the force whereas it should be 26.46 N

Thus, the correct answer is option E