Question

read about how isaac newtons observations led him to understand and explain the force of gravity.
isaac newton was sitting under an apple tree when he noticed an apple fall to the ground. this started him thinking about why objects always fall downwards. he thought that there must be a force that attracted the objects towards the ground. he called the force gravity.
newton thought further about gravity and the apple. he wondered if the same force at work on the apple was also at work on the moon. if it was, why did the apple fall down to the earth but the moon didnt?
newton calculated the force needed to keep the moon moving around the earth. then he compared it with the force that made the apple fall downwards. newton eventually came to the conclusion that, in fact, the apple and the moon were influenced by the same force. this was the force of gravity. but because the moon is so far way, the earths force of gravity is not strong enough to pull it down. instead, it holds the moon in a pathway, or orbit, around the earth.
1 what evidence made newton suggest the idea of gravity?
2 a explain what gravity is.
b what units do we use to measure the force of gravity?
3 how did newton explain the fact that the moon doesnt fly off into space?
challenge
why do you think the moon does not fall down onto the earth?

Explanation:

1. Newton noticed an apple fall to the ground, which made him think about a force attracting objects downwards, leading to the idea of gravity.

2a. Gravity is a force that attracts objects towards each other, especially towards the center of a planet like Earth.
2b. The unit to measure the force of gravity is the Newton (N), named after Isaac Newton.

1. Newton explained that the Earth's force of gravity holds the Moon in an orbit around the Earth instead of letting it fly off into space. For the challenge, the Moon doesn't fall onto the Earth because the gravitational - pull of the Earth provides the centripetal force needed to keep the Moon in a curved path (orbit) around the Earth, and the Moon's forward motion keeps it from simply falling straight down.

Answer:

1. He noticed an apple fall to the ground.

2a. A force that attracts objects towards each other, especially towards the center of a planet.
2b. Newtons (N)

1. The Earth's force of gravity holds the Moon in an orbit around the Earth.

Challenge: The Earth's gravitational - pull provides centripetal force for the Moon's orbit and its forward motion prevents it from falling straight down.