Turn on thread page Beta
    • Thread Starter
    Offline

    1
    ReputationRep:
    Something I've never understood is why falling objects accelerate. All my time searching online has just given me the same answer of, because F=ma, and the earth is applying a force to the falling object. Yes! I know that! But why would the speed of the object increase? I know as the object gets closer to Earth the force on it will be slightly greater, but I don't think that's the answer.

    In a different scenario (outer space), why would an object with two joules of energy accelerate, it's getting no more energy?
    Offline

    21
    ReputationRep:
    (Original post by Cyan Ink)
    Something I've never understood is why falling objects accelerate. All my time searching online has just given me the same answer of, because F=ma, and the earth is applying a force to the falling object. Yes! I know that! But why would the speed of the object increase? I know as the object gets closer to Earth the force on it will be slightly greater, but I don't think that's the answer.

    In a different scenario (outer space), why would an object with two joules of energy accelerate, it's getting no more energy?
    Intriguing question! To partially answer your question we need tounderstand the necessity of F=ma. (Let's assume Newton'sfirst law to be true!). Assuming there are no external forces, such asgravity and friction, consider an object at rest. It will never start to move unless we push it, andwe know that once we have pushed the object will carry one moving forever with thesame velocity at which it left our hand, it's velocity will neverincrease. But thinking about it again, the object changed velocity from 0m/sto a particular velocity when we pushed it. In other words, the object accelerated. A force was required to accelerate the object otherwise the object would stay still forever or carry one moving with a constant velocity if we stopped pushing it, but it would still accelerate if we kept pushing it. This is very important. This idea allows us to distinguish a quantity such as force.

    As a result, gravity is considered to exert a force on bodies as it was used to explain the motion of moon (and the planets) as they were orbiting, and not moving in a straight line, around the earth (or the sun).
 
 
 
Reply
Submit reply
Turn on thread page Beta
Updated: October 20, 2015

1,328

students online now

800,000+

Exam discussions

Find your exam discussion here

Poll
Should predicted grades be removed from the uni application process

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Write a reply...
Reply
Hide
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.