Question

Position of a body changes according to equation
x = 8 + 2t2 + 4. The speed of body at t = 2 seconds
is (x is in metre and t is in second)
(1) 20 m/s
(2) 10 m/s
(3) 8 m/s
(4) 5 m/s

Give ans with proper explanation.. ​

Answer 1

x = 8 + 2t²+4 = 12+2t²

We know Differentiation of displacement gives instantaneous velocity,

v = dx/dt => d12+2t²/dt

=>d12/dt + d2t²/dt

=>0 + 2×2t²-¹

=>0+4t

=>4t

Velocity at t = 2seconds,

4t = 4×2 = 8 m/s

The correct option is 3)8m/s

Cheers!

Answer 2

I hope this will help