Question

an object of mass 1 kg moving along x axis with constant speed 8 metre per second a constant force of 2 newton is applied positive Y direction find its speed after 4 seconds.

Answer 1

Hola!!!

Given ___________

Vx = 8 
Fy = 2N 
It is known to us that,
F = ma 
2 = 1 × a 
a = 2 m/s² In y - direction , 
by using vector kinematic formula we'll get
V = U + at 
Given Here
U = 8i 
a = 2j 
t = 4 
V = 8i + 2j × 4 = 8i + 8j 
⇒ Final velocity = 8i + 8j 
Speed = | velocity| 
Speed = √(8² +8²)
           = √(2×8²) 
            = 2√8 m/s 

Hope it helps to you.

$= = = = = = =$

Answer 2

acceleration in y direction= 2÷1=2m/s then we find velocity in y direction at 4 sec.v= u+at then v in y direction is 8m/s and then we find resultant which is unroot 64+64=8root3