Turn on thread page Beta
 You are Here: Home >< Physics

# suvat question watch

1. if an object is released from rest and hit the ground, why isn't both initial and final velocity 0?
but that logic doesn't seem to work in my prep
2. (Original post by alvan15)
if an object is released from rest and hit the ground, why isn't both initial and final velocity 0?
but that logic doesn't seem to work in my prep
The SUVAT equations are derived for a point mass undergoing a constant acceleration.

If an object hits the ground at a non-zero velocity, it is subject to an force in the direction opposite to its velocity i.e. there is a non-constant acceleration.
3. (Original post by pleasedtobeatyou)
The SUVAT equations are derived for a point mass undergoing a constant acceleration.

If an object hits the ground at a non-zero velocity, it is subject to an force in the direction opposite to its velocity i.e. there is a non-constant acceleration.
so are you suggesting that either initial or final velocity has to be 0?
4. (Original post by alvan15)
so are you suggesting that either initial or final velocity has to be 0?
objects with mass can't stop instantly, typically it'll hit the floor and start to compress. Could be a very rapid deceleration but not instant.

this type of question is usually asking about the instant the falling object contacts the floor, which is it's greatest velocity.

have to be quite general cos you haven't posted the question you're having trouble with.
5. (Original post by alvan15)
so are you suggesting that either initial or final velocity has to be 0?
No, I didn't suggest that, it was you who stated it originally - although it is the case.

I'm stating that the SUVAT equations are not valid for the problem you described since the impact of a point mass with a solid, immovable surface does not constitute an event where the acceleration of the system is constant.

The acceleration is not constant for all time and for this scenario, the acceleration can be modeled with the concept of impulse, which you may or may not have covered yet.
6. (Original post by pleasedtobeatyou)
No, I didn't suggest that, it was you who stated it originally - although it is the case.

I'm stating that the SUVAT equations are not valid for the problem you described since the impact of a point mass with a solid, immovable surface does not constitute an event where the acceleration of the system is constant.

The acceleration is not constant for all time and for this scenario, the acceleration can be modeled with the concept of impulse, which you may or may not have covered yet.
yes i have, thank you, i get it now

Reply
Submit reply
Turn on thread page Beta

### Related university courses

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: February 8, 2017
Today on TSR

### Edexcel C2 Core Unofficial Markscheme!

Find out how you've done here

### Everything you need to know for GCSE maths

Poll

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.