Physics:
1. What is meant by the statement “rest and motion are relative”. Give an example to show it?
2. Explain whether the walls of class room are at rest or in motion.
3. Define scalar and vector quantities.
4. Identify the following as scalar or vector quantities:
mass,velocity,speed,length,distance,displacement,temperature,force,weight,power,work and energy.
5. The school of a boy from his home is 1km to the east.When he reaches back home,he says that he had travelled 2km
distance
but his displacement is zero. Justify your answer.
6. Under what condition,the average speed is equal to the magnitude of average velocity.
7. Can the average speed of a moving body be zero?
8. Can the average velocity of a moving body be zero? State examples?
9. A car covers a distance of 5km in 20mins.Find the velocity of the car in km/hr and also in m/s.
10. An object “p” is moving with constant velocity for 5mins.Another object “Q” is moving with changing velocity for
5mins.Out
of these two objects, which one has acceleration?Explain.
11. Can an object be accelerated if it is moving with constant speed? If yes,explain giving examples.
12. (i). When do you say that an object has positive acceleration?
(ii). When do you say that an object has negative acceleration?
13. What is a reference point?
14. Name the two physical quantities which can be obtained from velocity-time graph.
15. An electric train is moving with a velocity of 120km/hr.How much distance will it cover in 30sec?
16. Give differences between linear motion and circular motion.
17. A body moves around the sun with constant speed in circular path. Is the motion of the body uniform or
accelerated?
18. Name the physical quantity which remains constant during uniform circular motion.
19. name the physical quantity which changes during uniform circular motion.
20. An object has moved through a distance. Can it have zero displacement? Support your answer with an example?
Answers
Ans 3 scalar quantity - quantity which have only magnitude but no direction.
Vector-quantities which have both magnitude and direction.
And. 4.scalar-mass, distance, weight, power, work, energy, temperature.
Vector-quantities - force, speed, velocity,displacement, length.
Ans 13 the starting point of the body is called reference point.
Answer:
Rest and motion are the relative terms because they depend on the observer's frame of reference. ... So if two different observers are not at restwith respect to each other, then they too get different results when they observe themotion or rest of a body.
The walls of a classroom are at rest with respect to the Earth. You are also at restwith respect to the Earth, that's why walls do not to be moving to you, but is inmotion with respect to the person moving around it.
The quantity is either a vector or a scalar. These two categories can be distinguished from one another by their distinct definitions: Scalars are quantitiesthat are fully described by a magnitude (or numerical value) alone. Vectors arequantities that are fully described by both a magnitude and a direction
Mass- scalar, velocity- vector , speed- scalar, length- scalar ,distance- scalar
displacement- vector, temperature- scalar, force- vector , weight- vector
work – scalar, energy- scalar
His displacement is 0 because he started from his home & ended at his home. But he went to his school and again came back. So his distance travelled is 2km
When an objectmoves along a straight line in the same direction, its total path length is themagnitude of displacement. Hence its average speed is equal to themagnitude of average velocity
Yes, if distance can be zero then speed can also be zero.because speed is equals to distance (0) divided by time(x). so, 0/ x =0.
a=0.25km/min
c=250m/min
b=4.16m/s
d= 15 kmph
If it is moving with velocity 45km/hr .
then ,it traveled 45 km in 1 hr
Now ,convert it into metre per minute:-
= 45×1000/60
= 750 metre/minute.
so,it traveled 750 metre in 1 minute.
lastly,convert it into metre per second :-
= 750/60
= 12.5m/s
hence ,it traveled 12.5 metre in 1 second.
Object P is in constant velocity, thus there is no change in the velocity with the change in time. Hence velocity is zero, thus acceleration is also zero.
In object Q there is change in the velocity thus acceleration is caused in the object Q.
Explanation: