4.5.1.3 Gravity

Question 1

What is weight?

Answer 1

Weight is the force acting on an object due to gravity.

Question 2

What causes the force of gravity close to Earth?

Answer 2

The gravitational field around the Earth.

Question 3

What does the weight of an object depend on?

Answer 3

The gravitational field strength at its location.

Question 4

What is the equation to calculate weight?

Answer 4

W=m×g
Where:

W = weight (N)

m = mass (kg)

g = gravitational field strength (N/kg)

Question 5

What is the value of Earth’s gravitational field strength?

Answer 5

Approximately 9.8 N/kg (this value is usually given in exams).

Question 6

What is the relationship between weight and mass?

Answer 6

Weight is directly proportional to mass (W ∝ m).

Question 7

What is the ‘centre of mass’?

Answer 7

The point where the weight of an object is considered to act.

Question 8

What instrument is used to measure weight?

Answer 8

A calibrated spring-balance, also called a newtonmeter.

Question 9

A 10 kg object is on Earth (g = 9.8 N/kg). What is its weight?

Answer 9

W=m×g=10×9.8=98N