1. A ball of mass 150 g is dropped from a height of 7.0 m above the ground. Neglecting air resistance, determine the speed of the ball when it is at a height of 2.5 m above the ground. 2. A rock of mass m is dropped to the ground from a height h. It strikes the ground with kinetic energy Ki. A second rock, with mass 2m, is dropped from the same height. When the second rock strikes the ground, its kinetic energy is K2. What is the relation between K, and K2? (A)K1 = KI (B) K1 = 2K1 (C) K= = 4KI (D) K - WK (E)K=14 KI 3. A rock of mass m is dropped to the ground from a height h. It strikes the ground with kinetic energy Ki. A second rock, with mass m, is dropped from height 24. When the second rock strikes the ground, its kinetic energy is K2. What is the relation between Kj and K2? (A)Ki =Ki (B) K=2K) (C)K=4K) (D) Ki=WK (E)K A4 KI 4. The launching mechanism of a popgun consists of a trigger-released spring. The spring is compressed to a position ya, and the trigger is fired. The projectile of mass m rises to a position ye above the position at which it leaves the spring, indicated in the figure as position ye = 0. Consider a firing of the gun for which m = 35.0 g, ya - -0.120 m, and yc = 20.0 m. (a) Neglecting all resistive forces, determine the spring constant. (b) Find the speed of the projectile as it moves through the equilibrium position B of the spring.45. A bloc]: of mass l .6 kg is attached to a horizontal spring that has a force constant of Him as shown in the top figure. The spring is compressed 2.0 cm and is then release-:1 from rest as in the bottom figure. {a} Calculate the speed of the block as it passes through the equilibrium position .1" = I: t} if the surface is frictionless. r\" {b} Calculate the speed of the block as it passes through the equilibrium position if a constant friction force of 4.11} N retards its motion from the moment it is released. 5. A 6.0-kg block initially at rest is pulled to the right along a horizontal surface by a constant horizontal force of magnitude 12 N. (a) Find the speed of the block after it has moved 3.0 m if the surfaces in contact have a coefficient of kinetic friction uk = 0.15. (b) Suppose the force F is applied at an angle whose tangent is pik. Determine speed of the block after it has moved 3.0 m to the right