If a #2 kg# object is constantly accelerated from #0m/s# to #18 m/s# over # 5 s#, how much power musy be applied at #t= 2 #?

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Answer 1 · 2016-12-27T04:39:57

We use the relation #P=Fv# to show that the power applied at #t=2s# is 51.8 watts.

First, we find the acceleration of the object

#a=(Deltav)/(Deltat)=18(m/s)/(5s) = 3.6m/s^2#

This means the net force on the object is

#F=ma = (2kg)(3.6m/s^2) = 7.2 N#

To calculate power, we use the relation

#P=Fv#

To determine the velocity at #t=2s#, use an equation of motion

#v_f=v_i + a(Deltat)#

#v_f=0 + (3.6m/s^2)(2s) = 7.2 m/s#

Therefore the power applied at #t=2s# is

#P=Fv=(7.2N)(7.2m/s)=51.8 W#