[1 Mark Question Answer]

Question 11 Mark

Figure given below shows a velocity-time graph for a car starting from rest. The graph has three parts $AB, BC$ and $CD.$

State how is the distance travelled in any part determined from this graph .

Answer

Distance travelled in any part of the graph can be determined by finding the area enclosed by the graph in that part with the time axis.

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Question 21 Mark

Figure shows the displacement-time graph of two vehicles $A$ and $B$ moving along a straight road. Which vehicle is moving faster? Give reason.

Answer

Vehicle A is moving with a faster speed because the slope of line $A$ is more than the slope of line $B.$

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Question 31 Mark

What can you say about the nature of motion of a body if its displacement-time graph is A curve.

Answer

It depicts that the body is moving with variable velocity.

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Question 41 Mark

What can you say about the nature of motion of a body if its displacement-time graph is A straight line inclined to the time axis with an obtuse angle?

Answer

It depicts that the body is moving towards the starting point with uniform velocity.

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Question 51 Mark

What can you say about the nature of motion of a body if its displacement-time graph is A straight line inclined to the time axis with an acute angle?

Answer

It depicts that the body is moving away from the starting point with uniform velocity.

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Question 61 Mark

What can you say about the nature of motion of a body if its displacement-time graph is A straight line parallel to the time axis?

Answer

There is no motion, the body is at rest.

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Question 71 Mark

From the displacement-time graph of a cyclist given below in the Figure, find The time after which he reaches the starting point .

Answer

At $7\ s$ and $13\ s,$ the cyclist reaches his starting point.

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Question 81 Mark

State how the velocity-time graph can be used to find The displacement of the body in a given time.

Answer

The displacement of a body in a given time is given by the area enclosed between the velocity$-$time graph and $X-$axis $($with proper signs$).$

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Question 91 Mark

State how the velocity-time graph can be used to find The distance travelled by the body in a given time

Answer

The total distance travelled by a body in a given time is given by the area enclosed between the velocity-time graph and $X-$axis $($without any sign$).$

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Question 101 Mark

State how the velocity-time graph can be used to find
The acceleration of a body

Answer

The slope of the velocity-time graph gives the value of acceleration.

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Question 111 Mark

What does the slope of a displacement-time graph represent?

Answer

Slope of a displacement-time graph represents velocity.

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Question 121 Mark

For the motion with uniform velocity , how is the distance travelled related to the time ?

Answer

For the motion with uniform velocity, distance is directly proportional to time.

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Question 131 Mark

How is the distance related with time for motion under uniform acceleration such as the motion of a freely falling body?

Answer

For motion under uniform acceleration, such as the motion of a freely falling body, distance is directly proportion to the square of the time.

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Question 141 Mark

The velocity-time graph for a uniformly retarded body is a straight line inclined to the time axis with an obtuse angle. How is retardation calculated from the velocity-time graph?

Answer

retardation is calculated by finding the negative slope.

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Question 151 Mark

Figure shows the velocity-time graphs for two cars $A$ and $B$ moving in the same direction. Which car has greater acceleration? Give reasons to your answer.

Answer

Car $B$ has greater acceleration because the slope of line $B$ is more than the slope of line $A.$

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Question 161 Mark

What does the slope of velocity-time graph represent?

Answer

The slope of the velocity-time graph represents acceleration of the body.

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Question 171 Mark

When is the magnitude of displacement equal to the distance?

Answer

The magnitude of displacement is equal to distance if the motion of the body is one-dimensional.

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Question 181 Mark

A car moving on a straight path covers a distance of $1\ km$ due east in $100\ s.$ What is the speed of the car$?$

Answer

Speed of the car $=$ Distance/time taken
$=\frac{1 km }{100 s }=\frac{1000 m }{100 s }=10 m / s$

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Question 191 Mark

What do you mean by motion in one direction?

Answer

When a body moves along a straight line path, its motion is said to be one-dimensional motion.

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Question 201 Mark

Arrange the following speeds in increasing order. $10\ m s^{-1}, 1\ km \min^{-1}$ and $18\ km\ h^{-1}.$

Answer

$18\ km\ h^{-1} < 10\ m s^{-1} < 1\ km \min^{-1}$

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Question 211 Mark

When is a body said to be in motion?

Answer

A body is said to be in motion if it changes its position with respect to its immediate surroundings.

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Question 221 Mark

When is a body said to be at rest?

Answer

A body is said to be at rest if it does not change its position with respect to its immediate surroundings.

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Question 231 Mark

If a stone and a pencil are dropped simultaneously in vacuum from the top of a tower, then which of the two will reach the ground first? Give reason.

Answer

In vacuum, both will reach the ground simultaneously because acceleration due to gravity is same $(=g)$ on both objects.

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Question 241 Mark

'The value of $g$ remains the same at all places on the Earth's surface'. Is this statement true? Give reason for your answer.

Answer

No. The value of $'g'$ varies from place to place. It is maximum at poles and minimum at the Equator on the surface of the Earth.

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Question 251 Mark

Give one example of the following motion :
Uniform retardation

Answer

Example of uniform retardation: If a car moving with a velocity $'v'$ is brought to rest by applying brakes, then such a motion is an example of uniform retardation.

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Question 261 Mark

Give one example of following motion :
Variable acceleration

Answer

Example of variable acceleration: The motion of a vehicle on a crowded road is with variable acceleration.

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Question 271 Mark

Give one example of following motion :
Variable velocity

Answer

Example of variable velocity: A ball dropped from some height is an example of variable velocity.

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Question 281 Mark

Give one example of following motion : Uniform velocity

Answer

Example of uniform velocity : A body, once started, moves on a frictionless surface with uniform velocity.

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Question 291 Mark

Which of the quantity-velocity or acceleration-determines the direction of motion?

Answer

Velocity determines the direction of motion.

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Question 301 Mark

Distinguish between uniform velocity and variable velocity.

Answer

If a body travels equal distances in equal intervals of time along a particular direction, then the body is said to be moving with a uniform velocity. However, if a body travels unequal distances in a particular direction in equal intervals of time or it moves equal distances in equal intervals of time but its direction of motion does not remain same, then the velocity of the body is said to be variable $($or non-uniform$).$

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Question 311 Mark

When is instantaneous speed the same as the average speed?

Answer

Instantaneous velocity is equal to average velocity if the body is in uniform motion.

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Question 321 Mark

Which of the quantity-speed or velocity-gives the direction of motion of a body?

Answer

Velocity gives the direction of motion of the body.

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Question 331 Mark