The student switched on the driver unit and increased the rate of rotation until the coin slid off the turntable.
He read the angular velocity ω of the turntable from a digital display on the driver unit. He then replaced the coin in the original position on the turntable and repeated the procedure.
His results are shown.
ω / rad s-1 |
0.125 |
0.112 |
0.118 |
0.123 |
0.116 |
i)
The student used the results to calculate a mean value of ω.
State the purpose of calculating a mean.
(1)
ii)
Calculate the percentage uncertainty in the mean value of ω.
(3)
Percentage uncertainty = .......................................................
iii)
The student used ω and r to calculate the centripetal acceleration of the coin at the instant it started to slide.
Calculate the percentage uncertainty in this centripetal acceleration.
(3)
Percentage uncertainty = .......................................................