CBSE ADDA Science class 9th

**Q.1.**what is persistence of hearing? (1)

**Q.2.**what does the slope of speed-time graph indicate? (2)

**Q.3.**what is one Newton? (1)

**Q.4.**why will a sheet of paper fall lower than one that is crumpled into a ball? (2)

**Q.5**. A stone is dropped from the edge of a roof.

- How long does it take to fall 4.9m?

- How fast does it move at the end of that fall?

- How does it move at the end of 7.9m?

- What is its acceleration after 1 second and after 2 second? (4)

**Q.6.**A boy and a girl do the same work in 5 min and 10 min respectively. Which of these has more power and why? (1)

**Q.7. (a)**What name has been given to the force with which two objects lying a part attract each other?

**(b)**What happens to the gravitational force between two objects when the distance between them is:

**(i)**doubled

**(ii)**half (2)

**Q.8.**

**(a)**what is the condition for a force to do work on a body?

**(b)**A boy throws a rubber ball vertically upwards. What type of work, positive or negative is done.

**(i)**By force applied by boy?

**(ii)**By the gravitational force of earth? (3)

**Q.9.**name the characteristics of sound which depends on:

**(i)**Amplitude

**(ii)**waveform

**Q.10.**give one use of ultrasound in industry and one in hospitals? (1)

**Q.11.**A sonar station picks up a return signal after 3seconds. How far away is object? (speed of sound in water=1440m/s) (1)

**Q.12**. Name that part of ear which vibrates when outside sound fall on it? (1)

**Q. 13.**When the passenger m oving in a bus , the road side trees appear to b e moving ---------------------------------- (a) Back ward (b)For ward

**Q. 14.**In uniform motion the object covers ------------ (a) equel distance (b) un equal distance

**Q. 15.**Where objects cover un equal distances in equal interval of time then the motion is called ---------------- (a) uniform motion (b) non uniform motion

**Q. 16.**The average speed = =A car accelerate = (a) Total time taken /total distance traveled (b) Total distance traveled/total time taken

**Q. 17.**v = (a) t/s (b) s/t

**Q. 18.**An object travels 16m in 4sec and another 16 m in 2 sec. what is the average speed of the object----------- (a) 5.33 ms-1 (b) 5. 34 ms-1

**Q. 19.**If we specify , its direction of motion along with its speed , the quantity that specifies with the aspects is called------------- (a) velocity (b) motion

**Q. 20.**Automobiles are fitted with a device that show the distance traveled . such a device is known ---------- (a) odometer (b) Speedo meter

**Q. 21.**The velocity of an object can be -------------- (a) non uniform or variable (b) uniform or variable

**Q. 22.**Average velocity = (a) initial velocity + final velocity/ 2 (b) initial velocity + final velocity/1

**Q. 23.**Average velocity = (a) placement/ total time taken (b) Displacement/ total time taken

**Q. 24.**Acceleration = (a) change in velocity/ time taken (b) change in motion / time

**Q. 25.**S = (a) ut + 1/2at

^{2}(b) ut + 1 at

^{2}

**Q. 26.**A car accelerate uniformly from 18 km h

^{-1}to 36 km h

^{-1}in 5 sec . calculate the acceleration------------- (a) 1ms

^{-2}(b) 1 ms

^{-3}

**Q. 27.**A train starting from rest attaind a velocity of 72 km h

^{-1}in 5 minutes . Assuming that the acceleration is uniform. Find the distance traveled by the train for attaing this velocity --------------------------------- (a) 2km (b) 5 km

**Q . 28.**Define SI unit of force.(1)

**Q . 29.**A body is moving with a uniform speed of 15 m/s on a circular track. Why is its motion called acceleration motion.(1)

**Q . 30.**What is the distance travelled and displacement of a body as its moves from A to B via C.(2)

**Q . 31.**A motor boat starting from rest on a lake accelerates in a straight line at a constant rate of 2m/s2 for 4 seconds. How far does the boat travels during this time.(2)

**Q . 32.**Name the force which keeps various planets in their orbits. Write down the formula for the force which exists between two bodies of mass m1 and m2 separated by a distance R from each other.(2)

**Q . 33.**State Newton’s second law of motion. A ball is thrown on a smooth surface with a force and it stops after some time. Is it supporting First law of motion. Give reasons for your answers.(2)

**Q . 34.**Velocity-time graph of a body is given above. Answer the following questions (3)

- Which part of the graph shows uniform acceleration.
- Which part of the graph shows uniform retardation.
- Calculate the total distance travelled by the body.
- Which part of the graph shows zero acceleration.(3)

**Q . 35.**

- Derive the first equation of motion v=u + at graphically.
- Write the equation describing the principle of conservation of momentum.
- Why does the Gun recoil when a bullet is fired from it. (5)

## No comments:

## Post a Comment