When a force of 5n is applied to a spiral spring, it was stretched by 4mm. what would be the extension if the force is increased by 80%

7.2 mm

Explanation:

80% of 5 =( 80/100)×5 = 4N

new force 5+4= 9N

5N PRODUCES EXTENSION OF 4mm

9 N will produce extension x mm

this is a direct ratio

hence 5×x=9×4

              x= 36/5

               x= 7.2 mm

other method spring constant k =f/x= 5/4=1.25N/mmnew force = 5N +80% of 5=5+4 =9NAGAIN F=KXOR X = F/K= 9/1.25 = 7.2 mm

P

W= fd
where f is an applied force and d is the distance over which it is applied. when a parachuting skydiver is at constant velocity, he is experiencing "terminal velocity", the point at which his acceleration down is canceled out by air resistance. that means that the resisting force of the air is equal to his weight, but in the opposite direction. with this, we can solve for the work done by the force.
w = fd
w = (92.0)(9.81 m/s^2) (325)
w= 2.93 x 10^5 j
the value for work in this case is positive because it is pushing up on the skydiver, who has a downward force of gravity.
therefore the answer is 2.93 x 10^5 j