Only these three little questions for exam!

A 7.80-g bullet moving at 660 m/s strikes the hand of a superhero, causing the hand to move 4.60 cm in the direction of the bullet's velocity before stopping. (a) Use work and energy considerations to find the average force that stops the bullet. 36931 N (b) Assuming the force is constant, determine how much time elapses between the moment the bullet strikes the hand and the moment it stops moving. 0.13939 5 A 7000kg freight car rolls along rails with negligible friction. The car is brought to rest by a combination of two coiled springs as illustrated in the figure below. Both springs are described by Hooke's law and have spring constants with [(1 = 1700 N/m and k2 = 3600 N/m. After the first spring compresses a distance of 27.9 cm, the second spring acts with the first to increase the force as additional compression occurs as shown in the graph. The car comes to rest 55.0 cm after first contacting the twospring system. Find the car's initial speed. 0.3087 m/s kixz + k2\": ' 3'1) Total force (N) Distance (cm) An inclined plane of angle 9 = 20.0 has a spring of force constant k = 470 Mm fastened securely at the bottom so that the spring is parallel to the surface as shown in the figure below. A block of mass m = 2.57 kg is placed on the plane at a distance d = 0.270 m from the spring. From this position, the block is projected downward toward the spring with speed v = 0.750 m/s. By what distance is the spring compressed when the block momentarily comes to rest