A constant force of 2.5 N to the right acts on a 4.5 kg mass for 0.90 s.
(a) Find the final velocity of the mass if it is initially at rest.
. m/s to the right
(b) Find the final velocity of the mass if it is initially moving along the x-axis with a velocity of 11.5 m/s to the left.
. m/s to the left

(a)

(b)

Explanation:

(a) Since a constant external force is applied to the body, it is under an uniformly accelerated motion. Using the following kinematic equation, we calculate the final velocity of the mass  if it is initially at rest():

According to Newton's second law:

Replacing (2) in (1):

(b) In this case we have . So, we use the final velocity equation:

force required to detach it is given by

charges are taken to be fundamental charge

now we have

so above is the minimum distance at which it will detach

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