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Difficult Problems in Physics From post utme (UI 2006)
Physics
Chima Sunday (Tutor)
01-04-2016 15:51:00 +0000As rightly said that 'it is not over until its over' Note that the aim of this app is to see you celebrate your MATRICULATION, So in our own way in this room is to review some questions asked in some prominent schools that most people that attempted it failed it.
About 85% of students that attempted this questions failed it. Try it and see if you can get it right
Question 1. A simple pendulum makes 50 oscillations in one minute. What is the period of oscillation?
Option A 0.02s
Option B 0.20s
Option C 0.83s
Option D 1.20s
Question 2. A girl whose mass is 55kg stands on a spring-weighing machine inside a lift. When the lift starts to ascend, its acceleration is 2ms-2. What will be the reading on the machine? (Take g = 10ms-2 )
Option A 66kg
Option B 55kg
Option C 44kg
Option D 22kg
Solutions
Question 1
recall that we define period as the time it takes to complete one cycle,
here 50 oscillation = 60s
1 oscillation = ?
cross multiplying, we have that ? = (60s × 1 oscillation)/50 oscillations
thus ? = 60s/50 = 6s/5 = 1.2s, So correct option is D
Question 2
when descending from lift you loos some weight. This apparent loss in weight is dependent on the acceleration at which the lift is descending, thus the reaction
W = R - F, R = reaction on the foot of tthe girl = mass * gravity = mg. and F = force of the lift = mass * its accleration = ma and W is the weight on the spring
So W on the spring weighing machine = W = m(g - a) = 55(10 - 2) = 55 * 8 = 440N
converting Newton to kg we divide by 10, i.e 440/10 = 44kg
So correct option is C.
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Chima Sunday (Tutor)
Thumb up to you guys @Aminu Badamsi and Oduwale for that wonderful attempt. More especially @ Oduwale for having question 1 right. The questions have been updated with its solutions
0 04-04-2016 14:34:00 +0000
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tijjani kortoni
solution
T=n/t
where n = number of oscilation
t = time
T=50/60
T=0.83s0 03-09-2017 21:10:00 +0000
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