In: Physics
You are pushing a 6·kg block across a table so that it is speeding up with an acceleration of 2·m/s2.
(a) What is the net force acting on the block? ______N
(b) In addition to your push, the only other horizontal force acting on the block is friction. If your push has a magnitude of 20·N, what is the magnitude of the frictional force acting on the block? _______N
(c) If you want the block to stop accelerating and instead move
with a constant velocity, what will the magnitude of YOUR force
need to be? _______ N
a) It is given that the object is moving with an acceleration of 2m/s^2, which is the net acceleration due to all the forces acting on it( normal force, weight, applied force)
According to Newton's Second law,
.....................(1)
hence,
____________________________
b)We now have to calculate the force of frction acting on the block.
We are given,
We can substitute this in equation (1) to obtain the force of friction
ie,
(Assuming that the motion inin the positive x direction)
Now, (since there is not motion in the vertical motion)
Hence,
Taking magnitude,
_________________________________
c) The block will only stop accelerating and move with a constant velocity oly when the net force ating on the block is zero, ie when
ie,
The frictional force will be constant and only dependent on the wight of the object, hence we can carry over the value of the frictional force from part (b), ie
ie, The force applied to the block must have a magnitude of 8N applied in the positive x direction.