Table of Contents
How was the mass of the Earth determined for the first time?
The first person credited with “weighing” the Earth was Henry Cavendish (1731-1810.) In 1798 Cavendish measured the force between attracting lead spheres with a torsion balance. He knew the masses of the spheres and how far apart they were. He carefully measured the force between them, which allowed him to calculate G.
How did they find the mass of Earth?
The mass of the Earth may be determined using Newton’s law of gravitation. It is given as the force (F), which is equal to the Gravitational constant multiplied by the mass of the planet and the mass of the object, divided by the square of the radius of the planet.
How did Newton measure mass?
A newton is defined as 1 kg⋅m/s2 (it is a derived unit which is defined in terms of the SI base units). One newton is therefore the force needed to accelerate one kilogram of mass at the rate of one metre per second squared in the direction of the applied force.
What data would be required to estimate the mass of Earth?
Calculating g on Other Planets
Planet | Radius (m) | Mass (kg) |
---|---|---|
Venus | 6.073 x 106 | 4.88 x1024 |
Mars | 3.38 x 106 | 6.42 x 1023 |
Jupiter | 6.98 x 107 | 1.901 x 1027 |
Saturn | 5.82 x 107 | 5.68 x 1026 |
How did scientists calculate the speed of light?
The speed of light could then be found by dividing the diameter of the Earth’s orbit by the time difference. The Dutch scientist Christiaan Huygens, who first did the arithmetic, found a value for the speed of light equivalent to 131,000 miles per second. The correct value is 186,000 miles per second.
What is the formula to find the magnitude of the gravitational force between the Earth and object on the surface of the Earth?
Let the mass of the object = m. Distance between the the earth’s centre and object = Radius of the earth = R. Therefore, Gravitational Force = F = GMm/ R 2.
How was speed of light first calculated?
In 1676, the Danish astronomer Ole Roemer (1644–1710) became the first person to measure the speed of light. Roemer measured the speed of light by timing eclipses of Jupiter’s moon Io.