Question 5
A student measures the
time T for one complete oscillation of a pendulum of
length l.
Her results are shown
in the table.
l / m
T / s
0.420
± 0.001 1.3 ± 0.1
She uses the formula
T = 2π √(l/g)
to calculate the
acceleration of free fall g.
What is the best
estimate of the percentage uncertainty in the value of g?
A 0.02% B 4% C 8% D 16%
Reference: Past Exam Paper – November 2015 Paper 12 Q5
Solution:
Answer: D.
T = 2π √(l/g)
T2 = 4π2 l / g giving g = 4π2 l / T2
Percentage uncertainty in
g = (Δg / g) × 100%
Δg / g = (Δl / l)
+ 2(ΔT / T)
Δg / g = (0.001 / 0.420) +
2(0.1 / 1.3)
Δg / g = 0.156
Percentage uncertainty in
g = 0.156 × 100 % = 15.6 % ≈ 16%
thanks keep up the good work and i would very much like to see 2018 past papers solved
ReplyDeleteno problems. will try to add them later
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