Q20 of 21 Page 267

An object is moving along a straight line with uniform acceleration. The following table gives the velocity of the object at various instants of time


Plot the graph.


From the graph.


(i) find the velocity of the object at the end of 2.5 seconds.


(ii) Calculate the acceleration.


(iii) Calculate the distance covered in the last 4 seconds.


Following is the graph corresponding to the uniformly accelerated motion



a) Velocity at 2.5 seconds is 7 m/s.


b) Acceleration = slope of velocity time graph


=


= 2 m/s2


c) Distance covered in last 4 seconds is the area under the curve for last 4 second


i.e.


Total distance covered in last 4 seconds


= area under ABCD


= area of ABED + area of BCE


= ((6-0)*(6-2)) +


= 24 + 16


= 40 m


More from this chapter

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17

Define acceleration and state its SI unit. For motion along a straight line, when do we consider the acceleration to be (i) positive (ii) negative? Give example of a body in uniform acceleration.

 18

Find the total displacement of the body from the following graph:


 19

Instruction: The table given below shows distance (in cm) travelled by the bodies A, B and C. Read this data carefully and answer the questions which follow.

Distance (in cm) covered by different bodies



1. Which of the bodies is moving with


(a) constant speed?


(b) constant acceleration?


2. Which of the bodies covers


(a) maximum distance in 3rd second?


(b) minimum distance in 3rd second?


3. Which of the bodies is moving with non-uniform acceleration?


 21

Mehak was moving through the city roads towards her school by a car. She recorded the odometer reading of the car after every five minutes and plotted a graph for distance vs time. She then inferred about the type of motion and found average speed from the graph.

(a) Which qualities of Mehak are worth mentioning?


(b) What type of motion would she have inferred?


(c) How is average speed calculated from the graph?