Density & Buoyancy

Question 1

He piece of wood can float because the weight of the water displaced is _______________ the buoyant force.

Answer 1

Less than

Question 2

If cube A has a mass of 500 grams and cube B has a mass of 16 grams, will the cubes float or sink?

Cube A: Cube B:
5cm L 2cm L
5cm W 2cm W
5cm H 2cm H

How do you know?

D=M/V
V=LxWxH

Answer 2

Sink. Because 4 is greater than 1. (Water has the density of 1)

V= 5x5x5
V=125

D= 500g/125 cm3
D= 4

Question 3

What is the relationship between the density of water and temperature when water is heated from 40c to 60c? (Q13 chart)

Answer 3

As the temperature increases the density decreases.

Makes sense because heat energy causes molecules to speed up and spread out (gas).

Question 4

If an unknown force is pushing a piston downwards with a surface area of 100 cm3, the pressure in the piston increases to 3 N/cm2. What is the force that is applied to the piston?

F= pressure x surface area

Pressure = 3 N/cm2
Surface Area = 100 cm2

Answer 4

F= 3 N/cm2 x 100 cm2 (3N x 100)

Force = 300

Question 5

A piece of wood is floating in a beaker of water. The force acting upward on the piece of wood is known as?

Answer 5

Buoyant force