Question #b38a1

1 Answer
Dec 28, 2016

Answer:

#144N#

Explanation:

Let magnitude of the force be #F#,
Using Newton's second law of motion we obtain constant acceleration #a# as

#F=ma#

Inserting given value
#F=16a#
#=>a=F/16ms^-2# ......(1)

Assuming that initially the body is at rest, final velocity #v# of body after #3s# can be calculated with the help of kinematic expression

#v=u+at#

Inserting given values and using equation (1) we get
#v=0+F/16xx3#
#=>v=(3F)/16ms^-1# .....(2)

Once the force is removed the body moves at a constant velocity for next #3s#. Distance #s# covered in time is

#s=vt#

Inserting given values and using equation (2) we get
#81=(3F)/16xx3#
#=>F/16=9#

Solving for force we get
#F=9xx16=144N#