An object is at rest at #(2 ,4 ,1 )# and constantly accelerates at a rate of #4/5 m/s# as it moves to point B. If point B is at #(3 ,6 ,7 )#, how long will it take for the object to reach point B? Assume that all coordinates are in meters.

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Answer 1 · 2018-04-12T08:20:06

The time is #=4.0s#

The distance #AB# is

#AB=sqrt((3-2)^2+(6-4)^2+(7-1)^2)=sqrt(1+4+36)=sqrt(41)m#

Apply the equation of motion

#s=ut+1/2at^2#

The initial velocity is #u=0ms^-1#

The acceleration is #a=4/5ms^-2#

Therefore,

#sqrt41=0+1/2*4/5*t^2#

#t^2=5/2*sqrt41#

#t=sqrt(5/2*sqrt41)=4.0s#