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zorro
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Homework Statement
A particle of mass 5 kg in the x-y plane has its potential energy given by U=(-7x + 24y ) J where x and y are in metre. The particle is initially at origin and has a velocity u=(14.4i + 4.2j)m/s. Find the magnitude of force on the particle and speed of the particle at t=4s.
Homework Equations
The Attempt at a Solution
dU/dx=Fx
dU/dy=Fy
Therefore, Fx= -7N and Fy= 24N
Fnet = 25N
magnitude of u=15m/s
magnitude of acceleration=25/5=5m/s^2
Hence v=15+5x4=35m/s
But the answer is 25m/s