Kerala SCERT Class 8 Science Chapter 9 Motion Question Answer Solution Here. Kerala Board Class 8 Students can find Here 9th Chapter Motion Notes provide by our Teacher. Important Question Answer from Chapter 9 Motion.
- Board- Kerala Board.
- Class – 8.
- Subject – Science Part 1.
- Chapter – 9.
- Chapter Name – Motion.
- Topic – Question Answer Solution.
Question: (1) _______ is the length of the path travelled?
(a) Distance
(b) Displacement
Ans: – Distance.
Question: (2) __________ is the straight line distance from the initial position to the final position?
(a) Displacement
(b) Distance
Ans: – Displacement.
Question: (3) the physical quantities having both magnitude and direction are referred to as ___________?
(a) Vector quantities
(b) Scalar quantities
Ans: – Vector quantities.
Question: (4) the physical quantities of which the direction is not to be indicated are ___________?
(a) Scalar quantities
(b) Vector quantities
Ans: – Scalar quantities.
Question: (5) when b body travels along a straight line in the same direction, the magnitude of its distance displacement will __________?
(a) Equal
(b) Unequal
(c) Same
Ans: – Equal.
Question: (6) ___________ is distance travelled in unit time?
(a) Speed
(b) Velocity
(c) Time
Ans: – Speed.
Question: (7) __________ is the displacement in unit time?
(a) Speed
(b) Velocity
(c) Time
Ans: – Velocity.
Question: (8) if a body in motion covers equal distance in equal intervals of time, the body is said to have __________ speed?
(a)uniform
(b) Nun uniform
Ans: – uniform
Question: (9) if a body in motion covers unequal distance in equal intervals of time, the body is said to have __________ speed?
(a)Nun uniform
(b) Uniform
Ans: – Nun uniform.
Question: (10) acceleration is rate of change in ______?
(a) Velocity
(b) Speed
(c) Time
Ans: – Velocity.
VERY SHORT QUESTION:
Question: (1) what is meant by distance?
Ans: – Distance is length of the path travelled.
Question: (2) what is displacement?
Ans: – Displacement is straight line distance from the initial position to final position. It has both magnitude and direction. Its unit is metre cm.
Question: (3) when distance and displacement will be equal?
Ans: – When body travels along straight line in the same direction, the magnitude of its distance and displacement will be equal.
Question: (4) what is Nautical mile?
Ans: – Nautical mile is the unit for measuring the distance in the field of aviation and sea transportation. One nautical mile is 1.852 km.
Question: (5) what is uniform velocity?
Ans: – A body has uniform velocity if it covers equal displacement in same direction in equal intervals of time.
SHORT NOTE:
Question: (1) what is initial velocity and final velocity?
Ans: – The initial velocity of a body is zero whenever the body starts from rest or is subjected for free fall. The final velocity is zero when a body is thrown up, the final velocity will be zero when it reaches the topmost position.
Question: (2) what is uniform speed and non uniform speed?
Ans: – If body in motion covers equal distance in equal intervals of time, the body is said to have uniform speed. If it covers un-equal distance in equal intervals of time the body is said to have non uniform speed.
For more questions
1.) Define the followings.
a.) Distance-Distance is the length of the path travelled by the object.
b.) Displacement- Displacement is the straight line distance from the initial position to the final position. It has both magnitude and direction. The unit of displacement is meter.
c.) Uniform speed- when the body in motion covers equal distances in equal intervals of time, the body is said to have uniform speed.
d.) Non- uniform speed- If body covers unequal distance in equal intervals of time , the body is said to have non- uniform speed.
2.) What is the unit for negative acceleration?
Ans- the unit for negative acceleration is m/s2
3.) What is the running speed of cheetah?
Ans- the speed of cheetah 25m/s to 30m/s.
4.) If initial velocity is 0 and final velocity is 5 then what will be the change in velocity?
Ans- the velocity is calculate by the formula final velocity – initial velocity. So according to that here the change in velocity is 5
5.) What is acceleration? How to calculate it?
Ans- Acceleration is the rate of change in velocity. It is calculated by the formula
Acceleration = change in velocity/ time
6.) Give example of non-uniform velocity.
Ans- examples of non- uniform velocity – A train starting and moving out of the station
7.) How to calculate average speed?
Ans- the average speed is calculated by the formula
Average speed= Total distance travelled/ time taken to travel the distance
2.) answer the following in short.
1) explain uniform speed and non-uniform speed.
Ans- If a body in motion covers equal distances in equal intervals of time, the body is said to have uniform speed. If it covers unequal distances in equal of time, the body is said to have non- uniform speed.
2) Give the examples of uniform and non- uniform velocity.
Ans- Uniform Velocity example- when light travels through vaccum
Non- uniform velocity example- a train starting and moving out of the station.
3) what is Nautical mile. Explain
Ans- Nautical mile is the unit for measuring the distance in the field of aviation and sea transportation. One nautical mile is 1.852km. The unit for measuring the speed of aeroplanes and ships is knot. One knot is the speed taken to travel one nautical mile in one hour.
4) what is scalar and vector quantity. Give examples of scalar quantity and vector quantity.
Ans- when the displacement is placed by a object then it is necessary to indicate the direction along with the magnitude of the distance travelled. Such physical quantities having both magnitude and direction are referred to as vector quantities. Physical quantities of which the direction is not to be indicated are scalar quantities.
Example- the example of scalar quantity is speed.
The example of vector quantity is velocity.
5) Explain about displacement.
Ans- When a body travels along a straight line in the same direction, the magnitude of its distance and displacement will be equal.
Example- consider the person start for travelling from A position and finish at B position with the respective path this means the person goes with displacement.
3.) Answer the following in brief.
1) write notes on following with examples.
a) Distance- Distance is the length of the path travelled. It is between two objects. The examples of distance is suppose the person walk for 3km and stop at one place after some time he walk again for 2km and reached at the place where he wants to go then from that we can conclude the total distance is 5km.
b) displacement-displacement is the straight line distance from the initial position to the final position. It has both magnitude and direction. Its unit Both direction and magnitude. The unit of displacement is meter.
Displacement means move the object form one place to another place.
d) Acceleration- acceleration is the rate of change in velocity. It is vector quantity. The acceleration is happened due to gravity. So there for it is represented as letter g. The acceleration produced in an object falling down freely due to the gravitational force of the earth is the acceleration at the place.
For example- the motion of a coconut falling from a coconut tree.
A moving ball coming to rest.
e) Retardation-the rate in change of velocity is negative and this is opposite to acceleration this is called retardation. The retardation is negative acceleration. Its unit is m/s2. In other words we can say that oppose to velocity is the example of retardation . for example- when car drives apply break then velocity goes decrease and retardation happens.
2) A motor car covered 80 m in 10 sec and a motor bike covered 40m in 25 sec. Answer the following.
a) which motor covered a less distance in more time?
Ans- the motor car covered 80m in 10 sec
b) which motor has higher speed?
Ans- motor card has higher speed.
3) A car covered the first 500m distance with the speed of 10m/s, the next 1500 m with a speed 15m/s and the last 300m with a speed of 12m/s. calculate the average speed of the car.
Ans- for the average speed of car can calculate with the given formula
Average speed = total distance travelled by object/ time taken to travel the distance
Here the car covered 500m , then 1500m and the 300m so total distance travelled by car is 2300m
And the total time taken by the car is 10+15+12 m/s= 37
So according to formula= 2300/ 37 = 62.16m/s
4) a bike travelling with a speed of 30mdistance in 10 sec. what is its speed?
Ans- speed is the distance travelled in unit time. So for the above question
Speed= distance / time
30/ 10= 3m/s
4.) MCQ
1) — is the rate of change in velocity.
a) acceleration
b) speed
c) velocity
ans- a) acceleration
2) a train starting and moving out of the station is the example of non- uniform velocity.
Ans- true
3) the unit of retardation ——
a) m/s
b) m
c) m/s2
d) none of the above
ans- c) m/s2
4) when the direction of motion changes the velocity—-
a) increase
b) decrease
c) change
d) remain same
ans- c) change
5) when the distance travelled by the car from A to B is 5m/s in 5sec then the rate of change in velocity is what?
a) 1m/s2
b) 1m/s
c) 0m/s
d) 0m/s2
ans- a) 1m/s2