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### First Term Exam - Physics -Std 9 - Answer key

First Term Examination 2014
Answer Key – Physics Standard  9

1. Momentum
2. a. Greater massed body
b. Increase the Mass, and Increase the Velocity
3. a. C-compressions , R- rarefactions
b. Longitudinal wave
c. Sound wave
4. a. 2 m
b. 2 Hz
c. 4 m
5. a. (i) t = 20 sec (ii) f = 0.5 Hz
b. Period is inversely proportional to Frequency (when period increases frequency decreases)
c. Length of the pendulum
6. a. The ball E move forward
b. The balls E and D move forward
c. Law of conservation of momentum
7. a. action =rowing on the lake, reaction = boat moves
b. Newton's third law of motion
c. Launching the rocket, Walking on the road
8. a. We can reduce the force acting on the hand.
b. Rate of change of momentum increase, so the force also increase.
When the time decreases, the value of ' change in momentum by time' increase.
9. a. take a suitable scale
b. draw the graph
c. time required = 12.5 seconds
10. a.Take a tray with water. Place some thermocol balls on the water. Fix a hacksaw blade on a stand and fix a pin on the other end of the hacksaw touching on the water. When the hacksaw blade vibrate , ripples formed in the water and thermocol balls move up and down.
b. Waves are formed due to the disturbance in water. Particles vibrate perpendicular to the direction of the wave.
11. (A)
a. F = ma
acceleration a = F/m = 60/ 10 =6 m/s2
b. final velocity v = u +a t = 0 + 6 x 2 = 12 m/s
(B)
a. velocity v = u + at = 0 + 10 x 3 = 30 m/s
b. height = displacement s= ut + ½ at2 = 0 x 3 + ½ x 10x 3 x 3 =45 m
12. a. (i) = 2G, (ii)= ¼ G
b. Gravitational Constant
c. decreases

Arunbabu said...

Thanks

jyothis seby said...

thank u very much how can we take a printout from this it is very useful for us pls sent std 8.10 also so that we make sure our answers can we get a vedio presentation of image formation of concave mirrors of std 8

sudheer g.n said...