can some pls explain
13. An atomic nucleus at rest decays radioactively into an alpha particle and a different nucleus. What will be the speed of this recoiling nucleus if the speed of the alpha particle is 3.8 x 105 ms-1. Assume the recoiling nucleus has a mass 57 times greater than that of the alpha particle. (a) 1.9 x 103 ms-1 (b) 2.8 x 10 ms-1 (c) 4.7 x 103 ms-1 (d) 5.6 x 103 ms-1 (e) 6.7 x 103 ms-1 14. A 58.0 kg box is pushed down a gravel slope, inclined at 21.0, over a distance of 8.90m at constant velocity. What is the work done by the person on the box if the coefficient of friction is 0.910? (a) 16.3kJ (b) 2.45 kJ (c) 6.1 1 kJ (d) 7.32 kJ (e) 279 J The next three questions relate to the following information. A water slide of height h ends at a height of 1.50m above the water. A girl riding the slide, starts from rest at point A and lands in the water at point B, which is 2.50m from the base of the slide. We can assume the slide is frictionless. 1.50 m 2.50 m 15. What is the time the girl is in the air for? Assume the vertical component of velocity is zero as she leaves the slide. Tip: think back to the equations of kinematics. (a) 1.143s (b) 0.039 s (c) 0.274 s (d) 3.83 s (e) 0.553 s 16. Using conservation of energy, what is the height h of the water slide (see the figure as to what defines h)? (a) 1.04 m (b) 1.76m (c) 1.25 m (d) 1.56 m (e) 1.19m 34 17. If the height of the water slide was actually h = 3.20 m, and the girl gave herself an initial speed of 0.540 ms-1 at point A, what will be the horizontal distance between the base of the slide and the splashdown point ? (a) 2.90 m (b) 4.40 m (c) 3.35 m (d) 6.68 m (e) 5.23 m 18. A pendulum consists of a mass M hanging at the bottom end of a massless rod of length I that has a frictionless pivot at the top. A mass m moving as shown with velocity v, impacts M and becomes embedded. What is the smallest value of v sufficient to cause the pendulum to swing up to the horizontal orientation? M (a) (m + M)vgl/m (b ) (m + M) vgl/(2m) (c) 2(m + M)v gl/m (d) (m + M)v2gl/m The next three questions relate to the following information. A bullet with mass 4.00 g and a speed of 750.0ms-1 is fired at a block of wood with a mass of 0.0950kg. The block is at rest on frictionless surface and is thin enough that the bullet will pass straight through it and out the other side. Immediately after the bullet exits the block, the speed of the block is 29.0m s-1. Assume the masses remain fixed through the course of events. M m 19. What is the speed of the bullet immediately after it exits the block of wood? (a) 265 ms-1 (b) 104 ms-1 (c) 598 ms-1 (d) 61.3ms-1 (e) 89.4 ms-1
