7. An object with a weight of 19.6 N moves with a constant velocity of 20.0 m/s. A net force of 6.00 N is applied to the object in the direction of its motion for 4.00 seconds.
What is the final momentum of the object?

118.4kgm/s

Explanation:

Given parameters:

Weight of object  = 19.6N

          mass of object  = 19.6/9.8   = 2kg

Constant velocity  = 20m/s

Force applied  = 6N

Time taken  = 4s

Unknown:

Final momentum of the object  = ?

Solution:

To solve this problem, we use Newton's second law of motion;

           Ft  = m (v  - u)

F is the force applied

t is the time taken

m is the mass

v is the initial velocity

u is the time taken

           Ft  = mv  - mu

mv is the final momentum;

       So;

     Final momentum  = Ft + mu

 Final momentum  = (19.6 x 4) + (2 x 20) = 118.4kgm/s

reserve is the answer