3.7 - Free fall Amd

Question 1

Electromagnet and Trapdoor method

Answer 1

• steel ball is held with electromagnet
• current switches off, electro demagnetises, causing ball to fall
• this triggers a timer at the same time
• when ball hits trapdoor, to open, the electrical contact is broken and timer stops
• value of g calculated with height of ball and time taken, using s=halfat^2

Question 2

Why is there inaccuracy in this method

Answer 2

results may come lower than accepted value due to air resistance and the slight delay in the release of the steel ball because of the finite time taken for the magnet to demagnetise

Question 3

How can this method be improved

Answer 3

• using a larger mass of the steel ball
• a longer distance and time to drop
• repeating experiment with different ^ and calculate average to reduce the effect of random error on the results.

Question 4

Light gates method

Answer 4

• trapdoor has time delays so
• use light gates of two light beams above each other with detectors connected to a timer
• when the balls falls through the first beam, it interrupts the light and the timer starts.
• when it falls through the second cutting the beam, the timer stops
• the two light gates are separated with a known distance

Question 5

Taking pictures

Answer 5

• a small metal ball in a dropped from rest next to a metre ruler
• the fall is recorded on a camera in rapid fire repeating mode
• or could use, a strobe-scope
• this illuminates the scene with rapid flashes. The camera shutter is open, producing a photograph with multiple images of the falling ball
• the position of the ball at regular intervals is then determined by examining the recording

Question 6

Graph

Answer 6

Using s=0.5 a t^2,
Plot a displacement over time squared graph
This gives a gradient which is a/2