Core Practical 1

Question 1

what is this practical about

Answer 1

measuring the acceleration of a free falling object

Question 2

what are the two equations that will allow us to calculate the acceleration due to gravity

Answer 2

• s = (at^2 / 2) + ut

- v^2 = u^2 + 2as

Question 3

if u = 0ms-1 and acceleration = gravity, what would those two equations become

Answer 3

• s = (gt^2 / 2) + 0

- v^2 = 0 + 2gs

Question 4

what would s be more accurately called in this practical and how would the formulas be rewritten

Answer 4

• it would be height (h)
• h = gt^2 / 2
• v^2 = 2gh

Question 5

in method 1 what is the ball bearing held up by and at what height

Answer 5

• it is held up by an electromagnet

- at height h

Question 6

what happens when the switch is thrown

Answer 6

• the circuit is broken

- so the electromagnet stops working and the ball begins to fall

Question 7

what begins the instant the circuit is broken

Answer 7

the stopwatch in the circuit starts timing

Question 8

what does the ball bearing fall into eventually

Answer 8

the trap door

Question 9

what happens when the ball falls on the trap door

Answer 9

• the lower circuit is broken

- which ten stops the timer

Question 10

what is h measured with

Answer 10

a meter ruler

Question 11

why is the timing repeated several times

Answer 11

• so that an average of t can be calculated

- with a range on uncertainty if need be

Question 12

what variable would you be changing in order to get an array of results when repeating the experiment even more and why

Answer 12

• the height

- so you can draw a graph of t^2 against h

Question 13

how would you find the gradient of the line

Answer 13

• h = gt^2 / 2
• rearrange for t^ to give 2h / g
• so the gradient will bee 2 / g

Question 14

what is the concept of method 2 simply put

Answer 14

a cylinder is dropped down a clear plastic tube

Question 15

why is the cylinder dropped through a tube

Answer 15

• so that it cuts through a beam

- in which the total time that it took to cross the beam can be measured

Question 16

what are the two things that are manually measured in this method

Answer 16

• l, the length of the cylinder

- h, the height of the top of the plastic tube above the light gate

Question 17

after you have repeated it several times to get an average for t, how would you calculate the velocity of the cylinder passing through the light gate

Answer 17

v = l / t

Question 18

what would be the gradient of the line if a graph of v^@ against h was plotted

Answer 18

• v^2 = 2gh
• its already arranged for v^2
• so the gradient is 2g

Question 19

why have the gradients in both methods been like so

Answer 19

• because you dont include the h in your gradient
• as that is what already has a axis
• it is effectively taken out

Question 20

if you have no special equipment what method would you use

Answer 20

• you would use the same principle as method 1
• measure the time it takes for an object to fall a measured height with a stopwatch
• repeat for an average time
• repeat with varying heights using a meter rule