Page 100 - text book form physics kssm 2020

4. Scan the QR code, download and print Figure 3.21 from Download Figure 3.21
the website given. Complete it to determine the formula
for the mass of the Earth.

Newton’s Universal Law
Centripetal force
of Gravitation http://bt.sasbadi.com/p4094

F 1442443 F 1442443
=
=

Equate two equations

=
1442443

Cancel common factor, m

=
1442443

2πr
Substitute v =
T

=
1442443
Rearrange so that M becomes
the subject of the formula

Mass of the Earth M =

Figure 3.21 Determining formula for the mass of the Earth
Discussion:
1. What is the formula to determine the mass of the Earth?
2. Period of revolution of the Moon around the Earth, T is 2.36 × 10 s and radius of the
6
Moon’s orbit, r is 3.83 × 10 m. Calculate the mass of the Earth, M.
8
3. The Earth revolves around the Sun in a period of one year and the radius of the orbit is
1.50 × 10 m. Calculate the mass of the Sun.
11
94
94 3.1.6
3.1.6