Question

A car starts its journey from the origin with the velocity 20i m/s and moves in x-y plane with acceleration of (2i + 4tj) m/s². Then the speed of car at t = 2 s will be

Answer 1

vi is 20 m/s    t is 2 s      

now to find a so draw a right angle triangle taking 2 at base and 4 at perpendicular..by finding hypoteneus which is resultant acceleration which is 4.4

now we have ALL values...putting in equation

Vf=Vi+at

vf =20 + 4.4x 2

vf= 28.2

Comments

Answer ia 25.3

Answer 2

Given u = 20

a = \(2\hat i+4\hat j\)

|a| = \(\sqrt{4+16}\) 

|a| = \(\sqrt{20}\) 

v = u + at

v = 20 + \(\sqrt{20}\) x 2

v = 20 + 8.82

v = 28.82 m/s

Comments

Acceleration is time variable