each second,
EXERCISE-2(A)
Differentiate between scalar and vector quantities, 20. Distinguish between acceleration and retardation
giving two examples of each
21. Differentiate between uniform acceleration and
State whether the following quantity is a scalar or
variable acceleration
vector ?
22. What is meant by the term retardation Name is
(a) pressure (b) force
SI unit
(c) momentum (d) energy
23. Which of the quantity, Velocity or acceleration
(e) weight
(f) speed
determines the direction of motion ? A . Velocity
Ans. (a) scalar (b) vector (e) vector (d) scalar 24, Give one example of each of the following
(e) vector (f) scalar (a) uniform velocity (h) variable velocity
When is a body said to be at rest?
(c) Variable acocleration (d) uniform retardation
When is a body said to be in motion ?
25. The diagram (Fig. 2.6) below shows the pattern of
the oil on the road, dripping at a constant rate from a
What do you mean by motion in one direction?
moving car. What informations do you get from it
Define displacement. State its unit.
about the motion of the car ?
Differentiate between distance and displacement,
= CAR IN
Can displacement be zero even if distance is not
MOTION
zero ? Give one example to explain your answer
When is the magnitude of displacement equal to the
distance ?
Ans. Initially it is moving with a constant speed and
Ans. When the motion is in a fixed direction
then it slows down.
Define velocity State its unit
26. Define the term acceleration due to gravity
Define speed. What is its S.L. unit?
Slate its average value
Distinguish between speed and velocity
27. The value of & remains same at all pieces on the
earth surfacs'. Is this statement true Give reason
Which quantity, speed or velocity gives the direction
of motion of a body ?
for your answer
Ans. Velocity
Ans. No. The value of g is maximum at the poles
1. When is the instantaneous speed same as the average
and minimum at the equator on the earth surface
speed ?
If a stone and a pencil are dropped simultanicously in
Distinguish between uniform velocity and variable
vacuum from the top of a tower, which of the two
velocity
will reach the ground first? Give reason
3. Distinguish between average speed and average
Ans. Both will reach the round simultaneously
velocity
since acceleration due to gravity is same ( 8) on
Give an example of motion of a body moving with a both. Also, the opposing viscous force of air is absent
constant speed, but with a variable velocity, Draw a in vacuum
diagram to represent such a motion
8. Give an example of motion in which average speed
Multiple choice type:
is not zero, but average velocity is zero.
1. A vector quantity is
9. Define acceleration State its SL unit.l
(a) work (b) pressure
(c) distance id) velocity (d) velocity
35
Answers
Scalar Quantity:It has only magnitude no direction. Vector Quantity: It has both magnitude and direction. Scalar Quantity: 1 dimensional. ... Vector Quantity: Example: Velocity, displacement, acceleration etc
If the direction of both the 'rate of change of velocity' and velocity are same then the 'rate of change of velocity' is called acceleration. If the direction of 'rate of change of velocity' and velocity are opposite to each other then the 'rate of change of velocity' is called retardation
If an object's speed (velocity) is increasing at a constant rate then we say it has uniform acceleration. The rate of acceleration is constant. If a car speeds up then slows down then speeds up it doesn't have uniform acceleration.
When the velocity decreases with respect to time it is termed as retardation or decelerationIn reality negative acceleration is commonly called retardation ...
velocity
Answer:
Ans 1.
Scalar- These are physical quantities which are expressed only by their magnitude.
E.g.- mass, length
Vector- These physical quantities require the magnitude as well as the direction to express them, then only their meaning is complete.
E.g.- displacement, velocity.
Ans 2.
a) scalar
b) vector
c) vector
d) scalar
e) vector
f) scalar
Ans 3.
A body is said to be at rest of it does not changes its position with respect to its immediate surroundings.
Ans 4.
A body is said to be in motion if it changes it's position with respect to its immediate surroundings.
Ans 5.
When a body moves along a straight line path, it's motion is said to of one direction (or one dimensional).
Ans 6.
Displacement is the shortest distance from the initial to the final position of the body, it's direction is from the initial position to the final position.