Answer:
42
Explanation:
27.9+13+1.21=42.11
to a significant figure= 42
Frequency, , is defined as the rate of rotation, or the number of rotations in some unit of time. Angular frequency, , is the rotation rate measured in radians. These three quantities are related by f = 1 T = ω 2 π .
a) Speed of the Moon: 1025 m/s
The speed of the moon is equal to the ratio between the circumference of its orbit and the orbital period:
where
is the radius of the orbit of the Moon
is the orbital period
Substituting into the formula, we find
b) Centripetal force:
The centripetal force acting on the Moon is given by:
where
is the mass of the Moon
is its orbital speed
is the radius of the orbit
Substituting into the formula, we find
c) Gravitational force
The only relevant force that acts on the Moon, and that keeps the Moon in circular motion around the Earth, is the gravitational force exerted by the Earth on the Moon. In fact, this force "pulls" the Moon towards the Earth, so towards the centre of the orbit of the Moon, therefore it acts as source of centripetal force for the Moon.