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Home › Grade9 › Grade 9 CBSE › Physics › Motion › Motion Worksheet-16

Motion Worksheet-16

Motion Worksheet-16

 

  1. The physical quantity which given both, the speed and direction of motion of a body is called its……………

 

  1. A motorcycle has a steady……………. of 3 m/s2. This means that every………..its……….increases by…………

 

  1. Velocity is the rate of change of ………………It is measured in ……………..

 

  1. Acceleration is the rate of change of …………….It is measured in …………..

 

  1. What type of motion, uniform or non-uniform, is exhibited by freely falling body? Give reason for your answer.

 

  1. State whether speed is a scalar or a vector quantity. Give reason for your choice.

 

  1. Bus X travels a distance of 360 km in 5 hours whereas bus Y travels a distance of 476 km in 7 hours. Which bus travels faster?

 

  1. Arrange the following speeds in increasing order (keeping the least speed first):

(i) An athlete running with a speed of 10 m/s.

(ii) A bicycle moving with a speed of 200 m/min.

(iii) A scooter moving with a speed of 30 km/h

 

  1. (a) Write the formula for acceleration. Give the meaning of each symbol which occurs in it.

(b) A train starting from railway station attains a speed of 21 m/s in one minute. Find its acceleration.

 

  1. (a) what term is used to denote the change of velocity with time ?

(b) Give one word which means the same as ‘moving with a negative acceleration’.

(c) the displacement of a moving object in a given interval of time is zero. Would the distance travelled by the object also be zero? Give reason for your answer.

 

  1. An insect covers a distance of 100 metres in 50 hours. Calculate the average speed of it in km/h.

 

  1. A tortoise moves a distance of 100 metres in 15 minutes. What is the average speed of tortoise in km/h?

 

  1. If a sprinter runs a distance of 100 metres in 9.83 seconds, calculate his average speed in km/h.

 

  1. A motorcyclist drives from place A to B with a uniform speed of 30 km h–1and returns from place B to A with a uniform speed of 20 km h–1. Find his average speed.

 

  1. A motorcyclist starts from rest and reaches a speed of 6 m/s after traveling with uniform acceleration for 3 s. what is his acceleration?

 

  1. An aircraft traveling at 600 km/h accelerates steadily at 10 km/h per second. Taking the speed of sound as 1100 km/h at the aircraft’s altitude, how long will it take to reach the ‘sound barrier’?

 

  1. If a bus traveling at 20 m/s is subjected to a steady deceleration of 5 m/s2, how long will it take to come to rest?

 

  1. (a)    What is the difference between ‘distance travelled’ by a body and its ‘displacement’? Explain with the help of a diagram.

(b)    An ant travels a distance of 8 cm from P to Q and then moves a distance of 6 cm at right angles to PQ. Find its resultant displacement.

 

  1. Define motion. What do you understand by the terms ‘uniform motion’ and ‘non-uniform motion’? Explain with examples.

 

  1. (a) Define speed. What is the SI unit of speed?

(b) What is meant by (i) average speed, and (ii) uniform speed?

 

Answer:

  1. velocity

 

  1. Acceleration; second ; speed (or velocity); 3 m/s

 

  1. Displacement; m/s

 

  1. Velocity; m/s2

 

  1. Non uniform motion.

 

  1. Scalar quantity. Speed is distance/time.

 

  1. Speed of bus X = 72 km/h; Speed of bus Y = 68 km/h; So bus X travels faster

 

  1. 200 m/min < 30 km/h < 10 m/s

 

  1. (a) a = ( v – u)/t where u is the initial velocity, v is the final velocity and t is time taken by the body.

(b) 0.35 m/s2

 

  1. (a) Acceleration   

 (b) Retardation           

 (c) No. Because distance is a scalar quantity having magnitude only. It has no specified direction

 

  1. 0.002 km/h

 

  1. 0.4 km/h

100 × 60/(15 × 1000)

 

  1. 36.62 km/h

 

  1. 24 km h–1

2 × 30 × 20/ ( 20 + 30)

 

  1. 2 m/s2

V = u + at where u=0, v = 6m/s and t = 3 s.

 

  1. 50 s

 

  1. 4 s

V = u + at where u = 20 m/s, v = 0 m/s and a = -5 m/s 2.

 

  1. (a) When a particle completes one rotation in a circular path of radius r, the distance traveled = 2πr. But the displacement = 0, because the initial and final positions are the same. Suppose the particle traveled only from A to B. Then distance = πr, but displacement = 2r.

(b) 10 cm

 

  1. A body has a uniform motion if it travels equal distances in equal interval of time, no matter how small these time intervals.

A body has a non-uniform motion if it does not travel equal distance in equal intervals of time.

 

  1. It is the distance covered by a body in unit time.

It is the ratio of the total distance travelled (path length) by the object to the total time taken.

When a particle covers equal distances in equal intervals of time then it is said to be moving with uniform speed.