Question

63) A body covers 20 m in the first second, 25 m in the next second and 45
m in the third second. What is its average speed?
ve od
A) 10 m/s
B) 20 m/
sine
C) 30 m/s
D) 40 m/s,answer me please​

Answer 1

Answer:

As we have a formula of motion that distance covered in t th second is

s=u+a(2t−1)/2

12 = u + a(2*2 - 1)/2

=> 12 = u + 3a/2

=> 2u + 3a = 24

and

20 = u + a(2*4 - 1)/2

20 = u + 7a/2

=> 2u + 7a = 40

From 1 and 2:

a = 4

u = 6

Now, distance covered in 4s after 5th second = Distance covered in 9 seconds - distance covered in 5 seconds

= 6*9 + 1/2 * 4 * 9 * 9 - (6 * 5 + 1/2 * 4 * 5 * 5)

= 54 + 162 - (30 + 50)

= 136 m

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Answer 2

Answer:

Average velocity = total Distance ÷ time

So

$v = \frac{20 + 25 + 45}{1 + 1 + 1} = \frac{90}{3} = 30 \: \: \frac{m}{s}$