Model Test Paper മാതൃകാ ചോദ്യപേപ്പർ
A full paper in the Kerala Class 9 Physics pattern for this chapter. Work on paper with a timer before you look at the solutions.
Standard IX · Physics
Chapter 4 · ഗുരുത്വാകർഷണം · Gravitation
- The first 15 minutes are cool-off time: read every question and plan your answers; do not write.
- Answer all questions. Marks for each question are shown on the right.
- For numericals write Given → Formula → Substitution → Answer with unit.
- Take g = 9.8 m/s2 and G = 6.67 × 10−11 N m2/kg2 unless the question gives other values.
SECTION AAnswer all · 8 × 1 = 8 marks
1.
The value of the universal gravitational constant G, with its SI unit, is .
(1)2.
The SI unit of weight is .
(1)3.
If the distance between two bodies is doubled, the gravitational force between them becomes
(1)(a) double(b) half(c) one-fourth(d) four times
4.
The acceleration due to gravity at the centre of the Earth is .
(1)5.
1 kgwt = N.
(1)6.
An artificial satellite gets the centripetal force needed to go round the Earth from .
(1)7.
The force, directed towards the centre, that keeps a body moving in a circle is called .
(1)8.
The mass of an object on the Moon is 12 kg. Its mass on the Earth is .
(1)SECTION BAnswer all · 5 × 2 = 10 marks
9.
State the universal law of gravitation. Write it as an equation and say what each symbol stands for.
(2)10.
Find the weight of a 60 kg person (a) on the Earth (g = 9.8 m/s2) (b) on the Moon (g = 1.62 m/s2).
(2)11.
Two bodies attract each other with a force F. What will the force become if (a) the mass of one body is made three times, (b) only the distance between them is made half?
(2)12.
A stone tied to a string is whirled in a horizontal circle with uniform speed. (a) Is its velocity uniform? Why? (b) In which direction will the stone move if the string breaks?
(2)13.
A coconut falls from the top of a coconut tree and reaches the ground in 1.5 s. Find (a) the height of the tree (b) the speed of the coconut just before it hits the ground. (g = 9.8 m/s2)
(2)SECTION CAnswer all · 4 × 3 = 12 marks
14.
Write three differences between mass and weight.
(3)15.
Two fishing boats, each of mass 5 × 104 kg, are anchored 10 m apart in Kochi harbour. (a) Calculate the gravitational force between them. (b) Why don’t the boats move towards each other? (G = 6.67 × 10−11 N m2/kg2)
(3)16.
(a) Using F = GMm/R2 and the second law of motion, show that g = GM/R2. (b) Calculate g on the Earth (M = 6 × 1024 kg, R = 6.4 × 106 m, G = 6.67 × 10−11 N m2/kg2). (c) Why do a feather and a coin fall together in a tube from which the air has been removed?
(3)17.
Goods were weighed with a spring balance at Kochi, near the equator. The same goods were weighed again with the same spring balance in England, much nearer the North Pole. (a) Will the reading change? (b) Give the reason. (c) Would a common balance show any change?
(3)SECTION DAnswer all · 2 × 5 = 10 marks
18.
On the Moon (g = 1.62 m/s2) an astronaut throws a ball straight up with a velocity of 8.1 m/s. (a) How long does the ball take to reach its highest point? (b) Find the maximum height. (c) After how much time does it come back to the astronaut’s hand? (d) How high would the ball go if it were thrown with the same velocity on the Earth (g = 9.8 m/s2)? About how many times higher does it go on the Moon?
(5)19.
A 5 kg object hangs from a spring balance. (a) What is the reading (in newton) when the balance is held at rest on the Earth? (g = 9.8 m/s2) (b) The balance and the object are released and fall freely together. What is the reading now? Explain. (c) The International Space Station orbits 400 km above the Earth. Taking R = 6400 km, calculate g at that height. Why do the astronauts inside feel weightless although gravity acts on them?
(5)