Forces and Pressure

Question 1

What is the formula for weight, W?

Answer 1

W = mg, where m is mass (in kg) and g is the acceleration due to gravity (about 10 N/kg on Earth).

Question 2

True or False: Density is defined as mass per unit volume.

Answer 2

True
density = mass/volume

Question 3

What is the unit of pressure in the SI system?

Answer 3

Pascals (Pa)

Pressure = Force/Area

Question 4

Fill in the blank: Density = _____ / Volume.

Answer 4

Mass

Question 5

What is the standard acceleration due to gravity on Earth?

Answer 5

Approximately 9.81 or 10 m/s²

Question 6

Which of the following is a unit of density? A) kg/m³ B) N/m² C) J/kg

Answer 6

A) kg/m³

Think: density = mass (in kg) / volume (in m³)

Question 7

What does the symbol ‘g’ represent in the formula for weight?

Answer 7

The acceleration due to gravity.

Question 8

Fill in the blank: Pressure = Force / _____

Answer 8

Area (in contact)

Question 9

What physical quantity is measured in Newtons?

Answer 9

Force

Question 10

What is the relationship between mass and weight?

Answer 10

Weight is the force exerted by gravity on an object with mass.

Question 11

If an object has a mass of 10 kg, what is its weight on Earth?
Take g = 9.81 m/s²

Answer 11

W = mg
= 10 kg x 9.81 m/s²
= 98.1 N

Question 12

A 3 kg box with base area 5 m² resting on the floor exerts a pressure of ________ on the floor.
Take g = 10 N/kg.

Answer 12

Pressure
= Force / Area
= weight/base area
= mg/5
=(3x10)/5 = 6 Pa (or N/m²)

Question 13

True or False: An object with a density greater than that of water will float.

Answer 13

False

An object denser than water will SINK in the water.

Question 14

What is the density of a 50 g cube of side 1 cm each?

Answer 14

Density = mass/volume
= 50 g/(1x1x1) cm3
= 50 g/cm3

Question 15

Fill in the blank: The formula for density is _____ / Volume.

Answer 15

Mass

Question 16

Which of the following does NOT affect pressure in a fluid? A) Depth B) Density C) Shape of container

Answer 16

C) Shape of container

Question 17

What is the SI unit for mass?

Answer 17

Kilogram (kg)

Question 18

True or False: The weight of an object changes with its location in the universe.

Answer 18

True

W = mg so W depends on the gravitational strength g.

e.g. On the moon, g is approximately 1/6 that of the Earth’s g.

Question 19

Fill in the blank: An object will float if its density is _____ than the fluid’s density.

Answer 19

Less or smaller

Question 20

What is the primary factor that determines whether an object sinks or floats?

Answer 20

The density of the object compared to the density of the fluid.