IX--CLASS--PHYSICS WORKSHEET 4

ARMY PUBLIC SCHOOL, GOLCONDA

Class 9 – Physics - Ch 8 – Motion

(WORKSHEET - 4)

Subtopic –

·         RATE OF CHANGE OF VELOCITY- ACCELERATION

·         EQUATIONS OF MOTION.

EQUATION OF MOTION

WHERE,

t is the time interval

s is the distance moved during this time

u is the velocity at the start

v is the velocity at the end

a is the (constant) acceleration

MCQs

1.  Which of the following statements is correct?

(a) both acceleration and velocity are same
(b) acceleration is a scalar and velocity is a vector
(c) acceleration is a vector and velocity is also vector
(d) none of these.

2.  When a body moves  in uniform motion, then:-

(a) its acceleration is zero

(b) its acceleration is positive

(c) its acceleration is negative

(d) none of these.

3.  Which of the following statements is correct?

(a)speed distance are scalar, velocity and acceleration are vector

(b) speed distance are vector, velocity and acceleration are vector

(c) speed and velocity are scalar, distance and velocity are vector

(d) speed and velocity are vector, distance and displacement are scalar

4.  m/s²  is S.I. unit of-

(a)  speed                                                        (c) acceleration

(b)  distance                                                    (d) time

5.  Acceleration of a moving body can be-

(a) can be positive
(b) can be zero
(c) can be negative
(d) all are true.

6.  Acceleration = velocity x time

(a)  True

(b)  false

(c)  both (a) and (b)

(d)  Neither (a) nor (b).

7.  Acceleration = velocity/time

(a)  True

(b)  false

(c)  both (a) and (b)

(d)  neither (a) nor (b).

8.  Acceleration = (u – v)/t

(a)  True

(b) false

(c) both (a) and (b)

(d) neither (a) nor (b)

9.  Acceleration = (v –u)/t

(a) True

(b) False

(c) both (a) and (b)

(d) neither (a) nor (b)

10.     The acceleration is _________ if it is in direction of velocity and ______ if it is in direction opposite to velocity.

(a) Positive, negative

(b) Negative, positive

(c) Negative, negative

(d)  Positive, positive

Q & A’s

1.  Define acceleration and mention its formula with S.I. units..

2.  When you will say a body is in

           (a) Uniform acceleration

           (b)  Non- Uniform acceleration

3.  State which of the following situations are possible and give example of each-

(a) An object with constant acceleration but zero velocity.

(b)  A uniform speed, but still have acceleration.

(c) A uniform speed, and zero acceleration.

(d)  Acceleration is in direction of motion.

(e) Acceleration in direction opposite to motion.

(f)   An object moving in a certain direction with an acceleration in the perpendicular direction.

4.  Differentiate velocity and acceleration.

5.  What is the acceleration of a body when it is moving with uniform velocity?

Solve the following

1.   State a relations between u, v, s, a and t. what each letter denotes?

2.  A bus decreases its velocity from  80 km/h to 60 km/h in 5 s. find the acceleration of the body.

3.  A train starting from a railway station and moving with uniform acceleration attains a speed 40 km/h in 10 minutes. Find its acceleration.

4.  A motor boat starting from rest on a lake accelerates in straight line at a constant rate of 3.00 m/s² for 8.0 s. how far does the boat travel during this time?

5.  A ball is gently dropped from a height of 20 m. if its velocity increases uniformly at a constant rate of 10 m/s^{2, .}With what velocity will it strike the ground? After what time will it strike the ground?

6.  A bus starting from rest moves with a uniform acceleration of 0.1 m/s² for 2 minutes. Find

(a) The speed acquired.

(b) The distance traveled.

7.  A train is travelling at a speed of 90 km/h. brakes are applied so as to produce a uniform acceleration of -0.5 m/s^2, find how far the train will go before it is brought to rest?

8.  A trolley while going down an inclined plane, has an acceleration of 2 cm/s².What will be its velocity 3 s after the start?

9.  A racing car has a uniform acceleration of 4 m/s².. What distance will it cover in 10 s after start?

10.   A stone is thrown in a vertically upward direction with a velocity of 5 m/s^. if the acceleration of the stone during its motion is 10 m/s².In the downward direction, what will be the height attained by the stone and how much time will it take to reach there?