- (a) velocity of the moving object
- (b) displacement covered by the moving object
- (c) speed of the moving object
- (d) acceleration of the moving object
Answer:
(b) displacement covered by the moving object
- (a) Motion of the Earth around the Sun
- (b) Motion of a toy train on a circular track
- (c) Motion of a racing car on a circular track
- (d) Motion of the hour hand on a clock dial
Answer:
(c) Motion of a racing car on a circular track
Answer:
(b)
Uniform motion is represented by a straight-line distance-time graph with constant slope.
- (a) a real force
- (b) the reaction force of centripetal force
- (c) a virtual force
- (d) directed towards the centre of the circular path
Answer:
(c) a virtual force
- Speed is a scalar quantity whereas velocity is a vector quantity.
- The slope of the distance-time graph at any point gives speed.
- Negative acceleration is called retardation or deceleration.
- Area under the velocity-time graph shows displacement.
If false, correct the statement.
Answer: False
Correct Statement:
The motion of a city bus in heavy traffic is an example of non-uniform motion.
Answer: True
Answer: True
Answer: False
Correct Statement:
The velocity-time graph of a freely falling body is a straight line inclined to the x-axis because velocity increases uniformly with time.
Answer: False
Correct Statement:
If the velocity-time graph is a straight inclined line, the displacement-time graph will be a curve because the body is uniformly accelerated.
Correction made:
Original answer marked as True was incorrect.
Choose the correct option:
- (a) Both assertion and reason are true and reason is the correct explanation.
- (b) Both assertion and reason are true but reason is not the correct explanation.
- (c) Assertion is true but reason is false.
- (d) Assertion is false but reason is true.
Assertion:
Accelerated motion may be due to a change in magnitude or direction of velocity or both.
Reason:
Acceleration can be produced only by change in magnitude of velocity.
Answer:
(c) Assertion is true but reason is false.
Assertion:
The speedometer of a car measures its average speed.
Reason:
Average velocity equals total displacement divided by total time taken.
Answer:
(d) Assertion is false but reason is true.
Correction Note:
A speedometer measures instantaneous speed, not average speed.
Assertion:
Displacement of a body may be zero when distance travelled is not zero.
Reason:
Displacement is the shortest distance between initial and final positions.
Answer:
(a) Both assertion and reason are true and reason is the correct explanation.
| List I | List II |
|---|---|
| Motion covering equal distances in equal intervals of time | Uniform motion |
| Motion with non-uniform acceleration | Non-uniform motion |
| Constant retardation | Negative acceleration |
| Uniform acceleration | Constant acceleration |
The original uploaded content was incomplete. The matching was logically completed based on standard textbook concepts.
Answer:
Velocity is the rate of change of displacement with respect to time.
- Velocity is a vector quantity.
- SI unit of velocity is (m/s).
| Distance | Displacement |
|---|---|
| Actual length of path travelled | Shortest distance between initial and final position |
| Scalar quantity | Vector quantity |
| Always positive | Can be positive, negative, or zero |
| Depends on path | Independent of path |
Answer:
An object is said to be in uniform motion if it covers equal distances in equal intervals of time.
| Speed | Velocity |
|---|---|
| Rate of change of distance | Rate of change of displacement |
| Scalar quantity | Vector quantity |
| Magnitude only | Magnitude and direction |
| Always positive | Can be positive, negative, or zero |
| SI unit: m/s | SI unit: m/s |
Answer:
When velocity decreases with time, acceleration becomes negative.
Negative acceleration is called:
- Retardation
- Deceleration
Answer:
Yes. In uniform circular motion, speed remains constant but direction continuously changes. Since velocity changes, the motion is accelerated.
Answer:
When an object moves with constant speed along a circular path, the motion is called uniform circular motion.
Examples:
- Earth revolving around the Sun
- Moon revolving around the Earth
First Equation of Motion
From velocity-time graph:
Rearranging,
This is the first equation of motion.
Second Equation of Motion
Displacement is equal to area under velocity-time graph.
This is the second equation of motion.
Third Equation of Motion
Using:
Substituting into:
We get:
This is the third equation of motion.
(i) Linear Motion
Motion along a straight line.
Example:
- Car moving on a straight road
(ii) Circular Motion
Motion along a circular path.
Example:
- Earth revolving around the Sun
(iii) Oscillatory Motion
To-and-fro motion repeated at regular intervals.
Example:
- Pendulum of a clock
(iv) Random Motion
Irregular and unpredictable motion.
Example:
- Movement of fish in water
Given:
(a) Final Velocity
Using:
(b) Time Taken
Using:
Answer:
- Final velocity = (20m/s)
- Time taken = (2s)
Given:
- Diameter = 200 m
- Radius = 100 m
- Time for one round = 40 s
- Total time = 2 min 20 s = 140 s
Speed
Distance Covered
Displacement
Number of rotations:
After 3.5 rotations, athlete reaches opposite side of circle.
Displacement = diameter = (200m)
Given:
Using:
Answer:
Distance covered = (200m)
Fixed and Movable Objects
Immovable Objects:
- Houses
- Trees
- Plants
Movable Objects:
- Birds
- Cars
- Buses
Observation:
- Bus in heavy traffic covers unequal distances in equal intervals of time.
- Train in uniform motion covers equal distances in equal intervals of time.
Conclusion:
- Bus → Non-uniform motion
- Train → Uniform motion
Observation:
- Distance through path ABC:
- Distance AC:
- Shortest path from A to D:
- Total distance in path ABCDA:
Observation:
- Stone and eraser reach ground almost together.
- Eraser falls faster than paper.
- Crumpled paper falls faster than plain paper.
Reason:
Air resistance depends on surface area exposed to air. Larger surface area experiences greater air resistance.
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