Question

!!!TOMMORROW IS MY EXAM!!!!!! !!!!URGENT HELP!!!!
PLEASE HELP ME .... IN THIS QUESTION WHERE I MARK... HOW IS IT CAME...!???? plsz solve in ur notebook..

Answer 1

hey dear
here is your answer ☆

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☞ we know, velocity = dx/dt
d(a + bt²) / dt

da/dt + d bt²/dt
here,
d a/dt is 0 because derivative of constant term is 0
and d bt²/ dt is bt ( because in derivative, whatever the power may be one is always subtracted from the power i.e. 2-1 = 1 now power becomes 1. now this will be multiplied)

so, 0 + 2bt => (2) (2.5) (t) => 5t

now taking limits of time, when t = 0
v = (5) (0) => 0
when t = 2, v = (5) (2) =>10m/s
x = a + bt² => a + 4b

when time, t = 4
x = a + 16 b

now displacement from time 2 to 4 s
=> (a + 16b) - (a + 4b)
=> 12b

now,
average velocity = 12b / (4-2)
=> 12b /2
=> (12) (2.5)/2
=>30/2
=>15 m/s

hope it helps ✌ ✌