Chapter-8
Types of Motion
Learning Card-1
I. Choose the correct answer:
1. Time period(T) and frequency(n) of the wave are related by
a)T=n b)T=1/n c)n/T=1 d)nT=2
2. The following is an example for non-mechanical waves is
a) Sound waves b) electromagnetic wave c) Water waves d) Tides
3. The relation among wavelength (λ) frequency (n) and wave velocity is
a) V=n/λ b) nλ=n c) v=λ/n d) v=nλ
4. Any object of hang by a thread is
a) Simple pendulum b) bob c) weight d) Rigid body
5. The periodic disturbance at a point in a medium is
a) Motion b) wave c) kinetic energy d) Friction
6. An example for transverse wave
a) Sound waves b) straight motion of a spring
c) Vibration of molecules in air d) Electromagnetic radiation.
II. Answer the following in a sentence each:
1. What are waves? which are the two types
The disturbance set up in a medium is called as a wave.
The two types of wave are
1. Mechanical waves. 2. Electromagnetic waves.
2. What are longitudinal waves? Give an example.
The waves in which particles of the medium vibrate parallel to the direction of motion. Ex. Sound waves
3. What are transverse waves? Give an example.
After The waves in which particles of the medium vibrate perpendicular to the direction of motion. Ex. Electromagnetic waves.
4. Write any two characteristics of wave motion?
The two characteristics of wave motion are
1. A wave is produced by a periodic disturbance.
2. When a wave propagates in a medium the particles vibrate afont their mean position and energy is transferred without the transfer of the particles of the medium.
5. What are mechanical waves? Give an examples.
The waves which need material medium for their propagation are called mechanical waves for their propagation are called mechanical waves. Ex. Sound waves
6. What is simple harmonic motion? Give an example.
The motion which repeats after regular intervals of time is called simple harmonic motion.
7. What are the uses of studying wave motion?
Study of wave motion helps us to why microwaves are used in ovens and how radio waves are used in radio stations etc.
8. Write any two applications of studying simple harmonic motion.
1. Simple harmonic motion of a pendulum was used for the measurement of time.
2. Tuning the musical instrument is done with the vibrating tuning fork which executes simple harmonic motion.
9. What is amplitude of a wave?
The maximum displacement of a particle form its mean position is called amplitude of a wave.
10. What is oscillations of simple pendulum?
One complete to and fro motion of the particle about its mean position is called oscillation.
11. What is time period of a simple pendulum?
Time taken by the body to complete one oscillation is called Time period.
12. What is the relation between time period and frequency of a simple pendulum?
T=1/n
T = time period, n= frequency
13. V is velocity, n is frequency and λ is the wave length of a wave, write the equation to relate these three.
V=n λ
v = velocity, n = frequency, λ = wave length
14. What are electromagnetic waves?
The waves which don’t need material medium for their propagation, produced by an acceleration of an electric charges are called Electromagnetic waves.
15. Simple harmonic motion can be used to measure time how?
Simple pendulum executes simple harmonic motion using this time can be measured.
16. What is transferred through a wave?
Energy is transferred through a wave.
17. Write the unit of the following: a. frequency b. wave length.
The unit of frequency is Hertz (HZ)
The unit of wave length is meter (m)
18. Which two factors affect the velocity of a wave?
Wave length and frequency affect velocity of a wave.
Learning Card-2
Answer the following questions:
1. A plastic ball put on water waves move up and down do not come to the edge. Why?
The plastic ball put on water wave move up and down because the water molecules during wave motion move up and down.
2. Briefly explain the method of transfer of energy from source to the observer in the case of sound waves?
As the source vibrates the particles of the medium neighboring to it vibrates which results in compressions and rarefaction of which compress the neighboring particles. This cycle continues and wave propagates.
3. Why oscillation of a simple pendulum is simple harmonic?
The oscillation of a simple pendulum is periodic because it repeats at regular intervals.
4. On what factors the time period of a simple pendulum depends?
The period of a simple pendulum depends on length of the pendulum and acceleration due to gravity.
5. If velocity of light wave is 3 × 108 ms-1 and its frequency is 2 × 1014 Hz, calculate the wavelength?
v = 3 × 108 ms-1
n = 2 × 1014 Hz
λ = ?
v=n λ
3 × 108 = 2 × 1014 × λ
λ= (3 × 108) / (2 × 1014)
λ= 1.5 × 10-6 m
6. The frequency of a wave is 2500Hz and its wavelength is 200nm calculate its velocity.
n = 250Hz
λ = 200nm
v=?
v = n λ
v= 2500 × 200 × 10-9
v= 500000 × 10-9
v = 0.0005ms-1
7. If the frequency of a wave is 20Hz, what is its time period?
n = 20Hz
T=1/n
T=1/20
T = 0.05s
8. Give two examples for motion which are imperceptible motion.
1. Motion of constituents of solid
2. The revolution and spin of the earth.
Learning Card-3
I. Choose the correct answer:
1. A wave has a frequency of 20Hz the distance between two consecutive compressions is 2m. The wave speed is
a) 20 m/s b) 30 m/s c) 40 m/s d) 50 m/s
2. In the following diagram, point B has
a) Maximum kinetic energy (K.E) minimum potential energy (P.E) and zero acceleration
b) Minimum K.E. Maximum P.E zero acceleration
c) Maximum K.E maximum P.E maximum acceleration
d) Minimum K.E minimum P.E maximum acceleration
3. The position of Halley’s comet after particular time can be predicted by applying to properties of
a) Circular motion b) Simple harmonic motion c) rotation d) Wave motion
4. The wavelength of transverse wave is 20cm. and its velocity is 10 m/s The frequency of the wave is
a) 150 Hz b) 20Hz c) 50Hz d)100 Hz
5. The velocity of a wave whose time period is 2s and wave length 5 m is
a) 1 m/s b) 1.5 m/s c) 10m/s d) 2.5 m/s
II. Answer the following questions:
1. Imagine that you are on the moon. If anybody challenges you to send sound from one place to another place on moon, how do you do it?
BY creating vibrations of the surface of the moon
2. Given here a diagram representing simple harmonic motion.
(i) At which point, the K.E is minimum at A.
(ii) At which point, the K.E is maximum at C.
(ii) At which point, the Acceleration is A+C minimum
(iv)At which point, the P.E is maximum at A
3. At any point in the path of the simple pendulum the sum of K.E and P.E remains same. Justify In case of a simple pendulum.
As K.E increases from A to C but potential energy decreases, becomes minimum at c. hence the sum of P.E and K.E is always a constant
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