Question

A particle at origin (0, 0) moving with initial velocity u= 5 m/s j and acceleration 10i+4j. After t time it reaches at position (20, y) then find t and y? ​

Answer 1

A particle at origin (0,0) moving with initial velocity u = 5 m/s j and acceleration 10i + 4j. after t time it reaches at position (20, y)

We have to find t and y.

solution : using formula, s = ut + 1/2 at²

here u = 5 j

a = 10i + 4j

s = 20i + y j [i.e., (20, y) ]

now, 20i + y j = (5 j) × t + 1/2 × (10i + 4j) × t²

⇒20i + y j = (5t) j + (5t² i + 2t² j)

⇒20i + y j = 5t² i + (5t + 2t²) j

on comparing we get,

20 = 5t² ⇒t = 2

and y = 5t + 2t²

putting t = 2

so , y = 5 × (2) + 2(2)² = 10 + 8 = 18

Therefore the values of t = 2 and y = 18