Question

The figure shows a person using flying equipment. The water inside this device is forced upward, exerting a vertically upward force on the person.


Say the necessary condition for the person to remain suspended in the air. (1 point)
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7 (b) The person weighs 700 N. And the equipment 140 N.
7 (b) (i) Calculate the combined mass of the person and the device. (g= 10 N/kg) (2 points)

Answer 1

• The upward force exerted by the water being forced out of the jetpack must be equal to the combined weight of the person and equipment.
• The combined mass of the person and the device is 84 kg.

(a) The necessary condition for the person to remain suspended in the air is that the upward force exerted by the water being forced out of the jetpack must be equal to the combined weight of the person and equipment. This is due to Newton's first law, which states that an object at rest or in uniform motion will continue in that state unless acted upon by an external force.

(b) (i) We can calculate the combined mass of the person and device using Newton's second law:

F = ma

This can be rearranged as:

m = F/a

With a total force of 840 N (700 N from the person and 140 N from equipment) and gravity acting at 10 N/kg, we have:

`$\[m = \frac{840 \, \text{N}}{10 \, \text{N/kg}} = 84 \, \text{kg}.\]`

So, the combined mass of the person and the device is 84 kg.