Question: On an object of mass 1 kg moving along x-axis with constant speed 8m/s, a constant force 2 N is applied in positive y- direction. Find its speed after 4 seconds.
Please explain how to solve the above question. The answer is 8√2m/s.
Speed along X axis is, vx = 8 m/s
Mass, m = 1 kg
Force applied, Fy = 2 N
Acceleration, ay = F/m = 2/1 = 2 m/s2
Now, along Y the body starts moving after application of the force.
Initial velocity along Y, uy = 0
So, using, v = u + at
=> vy = uy + ayt
=> vy = 0 + (2)(4)
=> vy = 8 m/s
So, magnitude of the resultant velocity is,
v = (vx2 + vy2)1/2 = (82 + 82)1/2 = 8√2 m/s