P5 - Investigating Motion Flashcards
State the Equipment needed for the investigating motion practical (newtons 2nd law)
- Trolley of known mass
- Piece of card
- Light gate connected to data logger ( or computer)
- Pulley
- Hook of known masses
- Masses
How do you complete the investigating motion practical (newtons 2nd law)?
1) Set up the appartus shown below. Set up the trolly so it holds a piece of card with a gap in
middle that will interrupt the signal on the light gate twice. If you measure the length of each bit of card that will pass through the light gate and input this into the software, the light gate can measure the velocity for each bit of card. It can use this to work out the acceleration of the trolley.
2) Connect the trolley to a piece of stringthat goes over a pulley and is connected on the other side to a hook (that you know the mass of and can add more masses to).
3) The weight of the book and any masses attached fo it will provide the accelerating force,equal to the mass of the hook (m) × acceleration due to gravity (e).
4) The weight of the hook and masses accelerates both the trolley and the masses, so you are investigating the acceleration of the system (the trolley and the masses together).
5) Mark a starting line on the table the trolley is on, so that the frolley always travels the same distance to the light gate.
6) Place the trolley on the starting line, holding the hook so the string is taut (not loose and touching the table), and release it.
7) Record the acceleration measured by the
light gate as the trolley passes through it.
This is the acceleration of the whole system
8) Repeat this twice to get the average acceleration
How do you investigate mass in the investigating motion practical?
To investigate the effect of mass, add masses to the trolley one at a time to increase the mass of the system. Don’t add masses to the hook, or you’ll change the force. Record the average acceleration for each mass
How do you investigate mass in the investigating motion practical?
To investigate the effect of force. you need to keep the total mass of the system the same, but change the mass on the hook. To do this, start with all the masses loaded onto the trolley, and transfer the masses to the hook one at a time, to increase the accelerating force (the weight of the hanging masses). The mass of the system stays the same as you’re only transferring the masses from one part of the system (the trolley) to another (the hook). Record the average acceleration for each force.
With newtons second law, how are you able to explain the results?
By adding masses to the trolley, the mass of the whole system increases, but the force applied to the system is the same.This should lead to a decrease in the gocoleration of the trolley, as a = F/m.By traneferring masses to the hook, you are increasing the accelerating force without changing the mass of the whole system. So increasing the force should lead to an increase in the acceleration of the trolley.
