Simple Harmonic Motion Self Test
Question 1
A large mass bobs up and down on a heavy spring. Initially the mass is at the top 20cm above its lowest position. The magnitude of its maximum speed is 31cm/s.
What is the amplitude for this motion?
A. 10cm
B. 20cm
C. 31cm
D. 40cm
E. 62cm
A. 10cm - Correct!
B. 20cm - No. That is the total displacement.
C. 31cm - No.
D. 40cm - No.
E. 62cm - No.
What is the angular frequency for this motion?
A. 0.00πrads−1
B. 0.25πrads−1
C. 0.50πrads−1
D. 0.75πrads−1
E. 1.0πrads−1
A. 0.00πrads−1 - No. If the speed is given by v(t)=−ωAsin(ωt) what is its maximum value?
B. 0.25πrads−1 - No. If the speed is given by v(t)=−ωAsin(ωt) what is its maximum value?
C. 0.50πrads−1 - No. If the speed is given by v(t)=−ωAsin(ωt) what is its maximum value?
D. 0.75πrads−1 - No. If the speed is given by v(t)=−ωAsin(ωt) what is its maximum value?
E. 1.0πrads−1 - Correct!
v=−ωAsinωt
Maximum value when sin=1
|vmax|=ωA
ω=|vmax|/A=31/10=3.1=1.0πs−1
Quesstion 2
A large mass bobs up and down on a heavy spring. Initially it is at the top. It achieves its maximum downward velocity of 94cms−1 in 0.25s from its release.
What are the period, angular freuqnecy, and amplitude for this motion?
T=
A. 0.25s
B. 0.5s
C. 0.75s
D. 1.0s
E. 2.0s
A. 0.25s - No. It hasnt gone through a full cycle.
B. 0.5s - No. It hasnt gone through a full cycle.
C. 0.75s - No. It hasnt gone through a full cycle.
D. 1.0s - Correct!
E. 2.0s - No. It has gone more than one full oscillation.
ω=
A. 0.00πrads−1
B. 0.50πrads−1
C. 1.0πrads−1
D. 1.5πrads−1
E. 2.0πrads−1
A. 0.00πrads−1 - No that is not correct. What is the relationship between ω and T?
B. 0.50πrads−1 - No that is not correct. What is the relationship between ω and T?
C. 1.0πrads−1 - No that is not correct. What is the relationship between ω and T?
D. 1.5πrads−1 - No that is not correct. What is the relationship between ω and T?
E. 2.0πrads−1 - Correct!
ω=2π/T=2π/1=2πs−1
A=
A. 15.0cm
B. 23.0cm
C. 94.0cm
D. 156cm
E. 188cm
A. 15.0cm - Correct!
B. 23.0cm - No. What is the expression for the maximum velocity?
C. 94.0cm - No. What is the expression for the maximum velocity?
D. 156cm - No. What is the expression for the maximum velocity?
E. 188cm - No. What is the expression for the maximum velocity?
vmax=−ωA
A=vmax/ω=94/2π=15cm
Question 3
A large mass bobs up and down on a heavy spring. At first, it is seen moving up with a maximum velocity of 47cm/s. When it is 8.7cm above the central position, its speed is half its maximum value.
What are the amplitude, and angular frequency for this motion?
A=
A. 5.0cm
B. 10cm
C. 15cm
D. 20cm
E. 25cm
A. 5.0cm - No. That is not correct. What are the expressions for the velocity and the maximum velocity?
B. 10cm - Correct!
C. 15cm - No. That is not correct. What are the expressions for the velocity and the maximum velocity?
D. 20cm - No. That is not correct. What are the expressions for the velocity and the maximum velocity?
E. 25cm - No. That is not correct. What are the expressions for the velocity and the maximum velocity?
v=−ωAsinωt
vmax=−ωA=47
v=47sinωt
23.5=47sinωt
sinωt=1/2
ωt=30∘
x=Acosωt
8.7=Acos30=0.866
A=8.7/0.866=10cm
ω=
A. 0.00πrads−1
B. 0.50πrads−1
C. 1.0πrads−1
D. 1.5πrads−1
E. 2.0πrads−1
A. 0.00πrads−1 - No. What is the relation for vmax?
B. 0.50πrads−1 - Correct!
C. 1.0πrads−1 - No. What is the relation for vmax?
D. 1.5πrads−1 - No. What is the relation for vmax?
E. 2.0πrads−1 - No. What is the relation for vmax?
vmax=−ωA
but A=10
ω=47/10=0.75(2π)