Posted by Jat on .
A particle is travelling with velocity (4i+5j)m/s. It undergoes an acceleration of magnitude 2.5m/s^2 in a direction given by the vector (3i4j). Find the velocity and displacement of the particle from its initial position after 4s.

Please help me with M1 kinematics! 
Jat,
In the direction of x
u = 4i, a= 2.5(3/5)
At t =4
v = u+at
v= 4 + 2.5 (3/5)4=4+6=10
In the direction of y
u = 5j, a= 2.5(4/5)
At t =4
v = u+at
v= 5 + 2.5 (4/5)4=58=3
Hence
V = 10i3j
Now we have initial and final velocities
r = 1/2(u +v)t
r = 1/2(4i+5j+10i3j)4
r = 2(14i+2j)
r = 18i+4j