Question

A body moves along x-axis such that its displace-
ment varies with time as given, x = 7 + 3t + 5.
The average velocity during 3rd second is
(1) 28 ms-1
(2) 42 ms-1
(3) 56 ms -1
(4) 15 ms-1​

Answer 1

Explanation:

Heya.........!!!!

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Given in the question :-

• Displacement is given to us as a function of time => x = 5t^2 + 3t + 7

Now we have to take out average velocity during 3rd second .

The main thing in this question is to notice that we have being asked average DURING 3RD SECOND i.e = between 2 and 3 second.

So now ,let us take out the value of displacement during 3rd sec

• Putting ' t ' = 2

=> 5×(2)^2 + 3×(2) + 7

=> 20 + 6 + 7

x1 => 33 m

• Putting ' t ' = 3

=> 5×(3)^2 + 3×3 + 7

=> 45 + 9 + 7

x2 => 61 m

Average velocity = ∆x / ∆t

=> ( 61 - 33 ) / (3 - 2 )

=> 28 / 1

♦ Average Velocity => 28 m/sec .

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