Annual Examination – Set 2 വാർഷിക പരീക്ഷ
A full annual-examination paper covering all eight chapters (Part 1 and Part 2). Print it on A4 paper and give it to the student with a timer; the answer key is printed separately.
ANNUAL EXAMINATION · MODEL PAPER · SET 2
Standard IX · PHYSICS ഭൗതികശാസ്ത്രം
Name:Roll No.:Division:
- The first 15 minutes is cool-off time. Use it to read the questions and plan your answers; do not write during this time.
- Answer all the questions. The score for each question is shown in brackets on the right.
- Read each question carefully before you answer. Answer in keeping with the score and the time.
- For numerical problems, write the given values, the formula, the substitution and the answer with its unit.
- Draw neat, labelled diagrams wherever needed. Use the values of constants given in the questions.
Section AAnswer all questions · 10 × 1 = 10 marks
1.
A ray of light passes from glass into water. It falls on the boundary obliquely, at an angle of incidence of 30°. In the water, the ray
[1](a) bends towards the normal(b) bends away from the normal(c) goes straight on without bending(d) is reflected back into the glass
2.
A ray of light passes obliquely from medium P into medium Q and bends towards the normal. Which statement is correct?
[1](a) Light travels faster in Q than in P.(b) P is optically denser than Q.(c) Q has a higher refractive index than P.(d) The angle of refraction is greater than the angle of incidence.
3.
Which of the following moves with uniform velocity?
[1](a) a stone dropped from a height(b) a bus leaving a bus stop(c) a child on a swing(d) light travelling through vacuum
4.
Pick the odd one out and give the reason: distance, speed, displacement, time.
[1]5.
The mass of an object is measured by comparing it with standard masses. The instrument used for this is the
[1](a) spring balance(b) common balance(c) platform balance(d) measuring cylinder
6.
More cargo is loaded on to a ship that is floating in a harbour. The ship
[1](a) rises a little out of the water(b) sinks a little deeper but keeps floating(c) stays at exactly the same level(d) sinks to the bottom at once
7.
Fill in the blanks: Relative density of a substance = density of the substance ÷ . Relative density has unit.
[1]8.
One ampere is equal to
[1](a) 1 joule per coulomb(b) 1 coulomb per second(c) 1 volt per ampere(d) 1 joule per second
9.
Which of these is a secondary (rechargeable) cell?
[1](a) a torch (dry) cell(b) a button cell in a watch(c) the battery of a mobile phone(d) a voltaic cell made with zinc and copper
10.
Which of these shows that sound can travel through liquids?
[1](a) A snake senses the vibrations of an approaching animal through the ground.(b) Dolphins and whales communicate with each other under the sea.(c) We hear the school bell when we are on the playground.(d) Astronauts in space talk to each other by radio.
Section BAnswer all questions · 8 × 2 = 16 marks
11.
A ray of light AO travels inside a glass block and meets the glass–air surface obliquely at O, as shown. (a) Copy and complete the diagram: draw the normal at O and the refracted ray in air, and mark the angle of incidence i and the angle of refraction r. (b) Which is greater, i or r? Why?
[2]12.
Ammu walks from her house H 300 m east to a shop S, and then 400 m north to her school C (figure). The straight-line distance HC is 500 m. The whole walk takes 500 s. Find (a) the distance she travels and her displacement (b) her speed and her velocity.
[2]13.
A bullet of mass 10 g moves with a velocity of 300 m/s. A ball of mass 5 kg rolls with a velocity of 0.5 m/s. (a) Find the momentum of each. (b) Which has more momentum?
[2]14.
A diver feels weightless for a moment after she leaves the diving board, until she enters the water. (a) What is meant by free fall? (b) Why does she feel weightless during this time, even though the Earth is still pulling her?
[2]15.
The relative densities of candle wax, aluminium and kerosene are 0.9, 2.7 and 0.81. (a) Which of the two solids, wax or aluminium, will float in water? Why? (b) Will a piece of wax float in kerosene? Give a reason.
[2]16.
A girl riding a bicycle has a kinetic energy of 625 J. The mass of the girl and the bicycle together is 50 kg. (a) Find her speed. (b) What will the kinetic energy be if she doubles her speed?
[2]17.
(a) Using the circuit symbol of a cell, draw a battery of three 1.5 V cells connected in series. Write its emf. (b) By mistake, the middle cell is put in the wrong way round. What will the emf of the battery be now?
[2]18.
The speed of sound in some media at 25 °C is given below (Table 8.3).
(a) Arrange the media in increasing order of the speed of sound. (b) What do you conclude about the speed of sound in solids, liquids and gases?
[2]| Medium | steel | air | sea water | helium |
|---|---|---|---|---|
| Speed (m/s) | 5944 | 347 | 1525 | 968 |
Section CAnswer all questions · 6 × 3 = 18 marks
19.
(a) Why do stars twinkle? (b) In the figure, just before sunrise, the Sun S is still below the horizon, yet the observer sees it at S′, above the horizon. Explain why. (c) Name the phenomenon behind both (a) and (b).
[3]20.
The position–time graphs of two cyclists A and B riding along a straight road in the same direction are shown. At t = 0, B is 30 m ahead of A. (a) What kind of velocity does each cyclist have? Give a reason. (b) Find the velocity of A and of B. (c) At what time, and at what position, does A catch up with B?
[3]21.
A carpenter’s hammer of mass 0.8 kg hits a nail at 5 m/s and comes to rest in 0.02 s. (Take the direction of the hammer’s motion as positive.) (a) Find the change in momentum of the hammer. (b) Find the average force exerted on the hammer by the nail. What does the negative sign show? (c) If a thick rubber sheet were placed on the nail head, the hammer would stop in 0.1 s. Find the force now. Which way is better for driving the nail in? Why?
[3]22.
A wooden block has a volume of 2000 cm3 and a mass of 1.2 kg. (Density of water = 1000 kg/m3; 1 m3 = 106 cm3.) (a) Find the density and the relative density of the wood. (b) The block is placed in water (figure). What volume of the block is under water when it floats? (c) The block is moved to a saturated salt solution (density 1025 kg/m3). Does it float higher or lower? Find the volume under the solution now.
[3]23.
(a) A body of mass m is at rest. A constant force F acts on it and it moves through a displacement s, reaching a velocity v. Show that the kinetic energy it gains is ½mv2. (b) What kind of energy is stored in (i) a stretched catapult (ii) a coconut hanging on a coconut tree?
[3]24.
In the circuit shown, the battery is made of two 1.5 V cells. When the switch K is closed, the ammeter reads 0.5 A and the voltmeter reads 3 V. (a) How are the two cells connected? Why? (b) How much charge flows through the bulb in 2 minutes? (c) How much work is done in moving this charge through the bulb?
[3]Section DAnswer all questions · 4 × 4 = 16 marks
25.
An autorickshaw with its driver has a total mass of 400 kg. Starting from rest on a straight road, it is pushed forward by a resultant (unbalanced) force of 600 N for 10 s. (a) Find its acceleration. (b) Find its velocity after 10 s. (c) Find its momentum after 10 s and the rate of change of its momentum. Compare this rate with the force. (d) Two passengers with a total mass of 200 kg get in. If the same resultant force acts, what is the new acceleration? What do you learn from this?
[4]26.
Chandrayaan-3 placed a rover on the Moon. Suppose a small rover has a mass of 30 kg. (g on the Earth = 9.8 m/s2; g on the Moon = 1.62 m/s2) (a) Find its weight on the Earth. (b) What are its mass and its weight on the Moon? (c) A small tool is dropped from a height of 3.24 m above the Moon’s surface and falls freely. How long does it take to reach the surface? (d) An astronaut on the Moon drops a feather and a hammer together from the same height. Which reaches the ground first? Why?
[4]27.
At an Onam celebration, a child sits on a swing. The total mass of the child and the seat is 25 kg. At the highest point A the seat is 0.8 m above its lowest point B (figure). Ignore air resistance; g = 10 m/s2. (a) Find the potential energy (taking B as the zero level) and the kinetic energy at A, where the swing stops for an instant. (b) Find the kinetic energy and the speed at B. (c) At what height above B will the speed of the seat be 2 m/s? (d) If nobody pushes, the swing slowly comes to rest. Does this mean that energy is destroyed? Explain.
[4]28.
On a monsoon evening, lightning strikes a coconut tree 1388 m away from Meena. (Speed of sound in air = 347 m/s; speed of light = 3 × 108 m/s.) (a) After how many seconds does she hear the thunder? (b) She sees the flash almost at once. Why? (c) On a hotter day, would the thunder from the same distance reach her sooner or later? Why? (d) The thunder reaches her as compressions and rarefactions in the air. Do the air particles near the lightning travel all the way to her ear? Explain.
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