Question

A block has a volume of 0.09 m3 and a density of 4,000 kg/m3. What's the force of gravity acting on the block in water?

A. 882 N
B. 3,038 N
C. 2,646 N
D. 3,528 N

Answer 1

The formula for net force is mass times the acceleration of an object.
F = ma
Where: m = mass
a = acceleration due to gravity (9.8 m/s^2)
F = Force

If you are pertaining to gravitational force, the acceleration of gravity is what you will consider which is 9.8 m/s^2

Now, you are given only the volume and density. We know that Density is mass over volume:


`Density = (mass)/(volume)`

Using this we can extract a formula for mass:


`Density x volume = mass`

The volume of your block is 0.09
`m^(3)` and your density is 4000
`(kg)/( m^(3))`

Now input that into our formula:

`4,000 x 0.09 = mass`

`360kg = mass`

Now that we know that mass = 360kg, we can now solve for our force.
F = ma
F = (360kg)(9.8m/s^2)
F = 3,528 N

The answer is then D.