Download App

Science One word answer.

Gravitation · Gujarat Board (GSEB) STD 9 (GSEB - English Medium). 77 questions.

Questions · Page 1 of 2

One word answer.

🎯

Test yourself on this topic

50 questions · timed · auto-graded

Question 11 Mark
What do you mean by buoyancy?
Answer
The upward force exerted by any fluid (liquid, gas) on an object is known as upthrust or buoyancy.
View full question & answer→
Question 21 Mark
What do you mean by acceleration due to gravity?
Answer
When an object falls freely towards the surface of earth from a certain height, then its velocity changes. This change in velocity produces acceleration in the object which is known as acceleration due to gravity denoted the letter g. The value of acceleration due to gravity is g = 9.8m/ s2.
View full question & answer→
Question 31 Mark
What do you mean by free fall?
Answer
Gravity of earth attracts every object towards its center. When an object is dropped from a certain height, it begins to fall towards Earth’s surface under the influence of gravitational force. Such a motion of object is called free fall.
View full question & answer→
Question 41 Mark
What is the acceleration of free fall?
Answer
Acceleration of free fall is the acceleration produced when a body falls under the influence of the force of gravitation of the earth alone. It is denoted by g and its value on the surface of the earth is 9.8m s-2.
View full question & answer→
Question 51 Mark
A car falls off a ledge and drops to the ground in 0.5 seconds.
Let g = 10ms-2, then
How high is the ledge from the ground?
Answer
Height of the ledge would be equal to the distance travelled. And hence, height of the ledge = 1.25m.
View full question & answer→
Question 61 Mark
 Explain why, if a stone held in our hand is released, it falls towards the earth.
Answer
This is because the earth exerts a force of attraction (called gravity) on the stone and pulls it down.
View full question & answer→
Question 71 Mark
What name has been given to the force with which two objects lying apart attract each other?
Answer
Gravitational force causes two objects lying apart attract each other.
View full question & answer→
Question 81 Mark
Define mass of a body. What is the SI unit of mass?
Answer
The mass of a body is the quantity of matter contained in it. The SI unit of mass is kilogram (kg).
View full question & answer→
Question 101 Mark
Name the scientist who gave the three laws of planetary motion.
Answer
Johannes Kepler gave the three laws of planetary motion.
View full question & answer→
Question 111 Mark
Define weight of a body. What is the SI unit of weight?
Answer
The weight of a body is the force with which it is attracted towards the centre of the earth. The SI unit of weight is newton (N).
View full question & answer→
Question 121 Mark
Which is more fundamental, the mass of a body or its weight? Why?
Answer
The mass of a body is more fundamental because mass of a body is constant and does not change from place to place.
View full question & answer→
Question 131 Mark
As the altitude of a body increases, do the weight and mass both vary?
Answer
Weight of the body varies with altitude; mass of an object is constant.
View full question & answer→
Question 141 Mark
Name the principle which gives the magnitude of buoyant force acting on an object immersed in a liquid.
Answer
Archimedes’ Principle.
View full question & answer→
Question 151 Mark
What is the scientific name of the ‘upward force’ acting on an object immersed in a liquid?
Answer
Buoyant force or upthrust.
View full question & answer→
Question 161 Mark
When an object is dropped from a height, it accelerates and falls down. Name the force which accelerates the object.
Answer
Gravitational force of the earth.
View full question & answer→
Question 171 Mark
Name the scientist who explained the motion of planets on the basis of gravitational force between the sun and planets.
Answer
Newton explained the motion of planets on the basis of gravitational force between the sun and planets.
View full question & answer→
Question 181 Mark
What are fluids? Name two common fluids.
Answer
Those substances which can flow easily are called fluids. All the liquid and gases are fluids, like water, air etc.
View full question & answer→
Question 191 Mark
What is the usual value of the acceleration due to gravity of earth?
Answer
Usual value of acceleration due to gravity, g = 9.8m/s2.
View full question & answer→
Question 201 Mark
Write down the weight of a 50kg mass on the earth. (g = 9.8 m/s2).
Answer
Weight, W = m × g =50 × 9.8 = 490N
View full question & answer→
Question 211 Mark
In which direction does the buoyant force on an object due to a liquid act?
Answer
Buoyant force on an object due to a liquid act s in the vertically upward direction.
View full question & answer→
Question 231 Mark
A body has a weight of 10kg on the surface of earth. What will be its weight when taken to the centre of the earth?
Answer
Its weight will be zero as value of g is zero at the centre of the earth.
View full question & answer→
Question 241 Mark
Name the property of earth which is responsible for extremely small acceleration being produced in it as a result of attraction by other small objects.
Answer
Extremely large mass of the earth.
View full question & answer→
Question 271 Mark
During a free fall, will heavier objects accelerate more than lighter ones?
Answer
No, acceleration is independent of the mass of the body during free fall.
View full question & answer→
Question 281 Mark
What causes buoyant force (or upthrust) on a boat?
Answer
The buoyant force on a boat is caused by the pressure of water ‘pushing up’ on the bottom of the boat.
View full question & answer→
Question 291 Mark

State the units in which pressure is measured.

Answer
Pressure is measured in newton per square meter (N/m2) i.e., Pascal (Pa).
View full question & answer→
Question 301 Mark

A mug full of water appears light as long as it is under water in the bucket than when it is outside water. Why?

Answer
A mug full of water appears light as long as it is under water because buoyant force acts on it which reduces its effective weight and makes it appear lighter.
View full question & answer→
Question 311 Mark

The density of a body is 800kg/m3. Will it sink or float when dipped in a bucket of water? (Density of water = 1000kg/m3).

Answer
The body will float when dipped in a bucket of water as its density is less than that of water.
View full question & answer→
Question 331 Mark

An iron nail sinks in water but it floats in mercury. Why?

Answer
An iron nail sinks in water but it floats in mercury because density of iron is more than that of water but less than that of mercury.
View full question & answer→
Question 341 Mark

Why does a block of wood held under water rise to the surface when released?

Answer
Because the weight of the block of wood is less than the weight of an equal volume of water. So when it is completely submerged in water, the upward buoyant force on it is greater than the downward gravitational force on it. Hence, the lock rises to the surface.
View full question & answer→
Question 351 Mark
Why does ice float in water?
Answer
The density of ice is less than that of water, so ice floats in water.
View full question & answer→
Question 361 Mark
Which force is responsible for the moon revolving round the earth?
Answer
Gravitational force is responsible for the moon revolving round the earth.
View full question & answer→
Question 371 Mark
lire relative density of mercury is 13.6. What does this statement mean?
Answer
The relative density of mercury is 13.6, this means that mercury is 13.6 times as heavy as an equal volume of water.
View full question & answer→
Question 391 Mark
What is the weight of a 1 kilogram mass on the earth? (g = 9.8m/s2).
Answer
Weight, W = m × g
1kg × 9.8m/s2 = 9.8N
View full question & answer→
Question 401 Mark
Name the scientist who gave he magnitude of buoyant force acting on a solid object immersed in a liquid.
Answer
Archimedes gave the magnitude of buoyant force acting on a solid object immersed in a liquid.
View full question & answer→
Question 411 Mark
What is the value of gravitational constant G (i) on the earth, and (ii) on the moon?
Answer
Value of gravitational constant G on the earth and the moon is = 6.67 × 10-11Nm2/ kg2
Note that the value of G always remains constant irrespective of the location.
View full question & answer→
Question 421 Mark
On what factor/factors does the weight of a body depend?
Answer
The weight of a body is directly proportional to its mass. It also depends on the acceleration due to gravity which varies from place to place.
View full question & answer→
Question 431 Mark
The gravitational force between two objects is F. How will the force change when the distance between them is reduced to $\frac{1}{4}\text{th}$?
Answer
We know, that the force of gravitation between two objects is inversely proportional to the square of distance between them.
That is,
$\text{F}\propto\frac{1}{\text{r}^2}$
Now when the distance between two objects is reduced to $\frac{1}{4}\text{th}$ that's is made $\frac{1}{4}$, then the force between them will become 16.
i.e. $\bigg(\frac{1}{\frac{1}{4}}\bigg)^2$
$=16$
View full question & answer→
Question 441 Mark
A stone resting on the ground has a gravitational force of 20N acting on it. What is the weight of the stone? What is its mass? (g = 10m/s2).
Answer
Weight of the stone = Gravitational force acting on it = 20N
Weight, W = m × g
20 = m × 10
m = 2kg
View full question & answer→
Question 451 Mark
Name these force:
The force which wears away two surfaces as they move over one another.
Answer
Force of friction.
View full question & answer→
Question 461 Mark
State the Kepler’s law which is represented by the relation $\text{r}^3\propto\text{T}^2.$
Answer
Kepler’s law of periods states that: The cube of the mean distance of a planet from the sun is directly proportional to the square of time it takes to move around the sun.
View full question & answer→
Question 471 Mark
When a golf ball is lowered into a measuring cylinder containing water, the water level rises by 3cm3 when the ball is completely submerged. If the mass of ball in air is 33g, find its density.
Answer
Volume of golf ball = rise in water level = 30 cm3
Density of ball $=\frac{\text{Mass of ball}}{\text{Volume of ball}}=\frac{33}{30}=1.1\text{g}/\text{cm}^3$
View full question & answer→
Question 481 Mark
Name the source of centripetal force that the moon requires to revolve around the earth.
Answer
The gravitational force is the source of the centripetal force that earth requires to revolve around the sun.
View full question & answer→
Question 491 Mark
What is the gravitational force between earth and an object called?
Answer
The gravitational force between an earth and an object Weight and it is equal to product of mass(m) and acceleration due to gravity(g).
View full question & answer→
Question 501 Mark
Name these force:
The force which pulled the apple off Isaac Newton’s tree.
Answer
Gravitational force.
View full question & answer→
Generate Paper FreeAll Gravitation topics
One word answer. - Science STD 9 Questions - Vidyadip