You are Here: Home >< Physics

Work energy power watch

1. Question - Describe how the measurements would be used to investigate the conservation of energy?
I know that, we should find out the masses of the trolley and mass, Need to find MGH so need to find out the distance between the ground and them mass, and KE can be calculated before that need to find V, which can be calculated using the distance and time taken to fall. But is there anything to do with the trolley? The mark scheme says, need to find the speed of the trolley and KE as well, whats the link right there? I am confused. Please explain the conservation of energy of this experiment.
And Any Idea about how the graphs will be? will It be a curve or a straight line?
2. (Original post by Gartley222)

Question - Describe how the measurements would be used to investigate the conservation of energy?
I know that, we should find out the masses of the trolley and mass, Need to find MGH so need to find out the distance between the ground and them mass, and KE can be calculated before that need to find V, which can be calculated using the distance and time taken to fall. But is there anything to do with the trolley? The mark scheme says, need to find the speed of the trolley and KE as well, whats the link right there? I am confused. Please explain the conservation of energy of this experiment.
And Any Idea about how the graphs will be? will It be a curve or a straight line?
For energy to be fully conserved, all of the gravitational potential energy in the system at the start, must be converted to kinetic energy at the end:

with no energy losses.
3. its actually a 4mark question!
i wanted to know what the trolley is doing? trolley is loosing ke and mass is loosing gpe too and gaining ke as well. why do i need to find the velocity of the trolley? as in the mark scheme says: find the mass and V of the trolley. i dont find the link there.
4. actually If i find the kinetic energy of the trolly and kinectic and gpe of the mass. what will i do with it? cant link KE of the trolley with mgh and ke of the mass.
5. (Original post by uberteknik)
For energy to be fully conserved, all of the gravitational potential energy in the system at the start, must be converted to kinetic energy at the end:

with no energy losses.
since trolley is loosing ke and the mass is gaining KE would it be equal and since mass is loosing gpe and gaining ke. would that be equal to? confused.
6. (Original post by Gartley222)
since trolley is loosing ke and the mass is gaining KE would it be equal and since mass is loosing gpe and gaining ke. would that be equal to? confused.
The mass of both the trolley and the suspended weight will provide the gpe.

They are both stationary at the start of the experiment.

They then both accelerate under gravity so both must accrue kinetic energy as the gpe converts.

At the start the energy in the system must all be potential. At the end, there is no more potential and everything is converted to kinetic.

Spoiler:
Show

The mass falls vertically, the trolley accelerates horizontally.

7. (Original post by uberteknik)
The mass of both the trolley and the suspended weight will provide the gpe.

They are both stationary at the start of the experiment.

They then both accelerate under gravity so both must accrue kinetic energy as the gpe converts.

At the start the energy in the system must all be potential. At the end, there is no more potential and everything is converted to kinetic.
okay i understood! okay so far what it seems like the loosing KE of the trolley converts gpe of the suspended weight to KE. wil the loss of KE of the trolley equal to gain of KE of the suspeneded mass?
8. (Original post by Gartley222)
okay i understood! okay so far what it seems like the loosing KE of the trolley converts gpe of the suspended weight to KE. wil the loss of KE of the trolley equal to gain of KE of the suspeneded mass?
?????

The trolley does not lose KE. It gains KE.

The trolley converts it's own gpe to KE.

The weight does not lose KE. It gains KE.

The weight converts it's own gpe to KE.

The weight is pulling the trolley !

Effectively, the mass of the trolley and the mass of the weight are summed.

They both move the same distance at the same time. The weight falls vertically and the trolley moves horizontally.
9. (Original post by uberteknik)
?????

The trolley does not lose KE. It gains KE.

The trolley converts it's own gpe to KE.

The weight does not lose KE. It gains KE.

The weight converts it's own gpe to KE.

The weight is pulling the trolley !

Effectively, the mass of the trolley and the mass of the weight are summed.

They both move the same distance at the same time. The weight falls vertically and the trolley moves horizontally.
thank you!!

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: October 5, 2017
Today on TSR

Congratulations to Harry and Meghan!

But did you bother to watch?

Why are girls so attracted to tall guys?

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