(II) An atomic nucleus initially moving at 320 m/s emits analpha particle in the direction of its velocity, and the remaining nucleus slows to 280 m/s If the alpha particle has a mass of 4.0 u and the original nucleus has a mass of 222 u, what speed does the alpha particle have when it is emitted?

(III) A 0.145-kg baseball pitched horizontally at 27.0 m/s strikes a bat and pops straight up to a height of 31.5 m. If the contact time between bat and ball is 2.5 ms, calculate the average force between the ball and bat during contact.

Professional Application - A 75.0-kg person is riding in a car moving at 20.0 m/s when the car runs into a bridge abutment. (a) Calculate the average force on the person if he is stopped by a padded dashboard that compresses an average of 1.00 cm. (b) Calculate the average force on the person if he is stopped by an air bag that compresses an average of 15.0 cm.

(III) A neon atom(m= 20.0 u) makes a perfectly elasticcollision with another atom at rest. After the impact, theneon atom travels away at a 55.6° angle from its originaldirection and the unknown atom travels away at a –50.0°angle. What is the mass (in u) of the unknown atom?[Hint: You could use the law of sines.]

(II) Three cubes, of side lo, 2l,, and 3l,, are placed next to one another (in contact) with their centers along a straight line as shown in Fig. 7–38. What is the position, along this line, of the CM of this system? Assume the cubes are made of the same uniform material. x = 0 --- FIGURE 7-38 Problem 52. –3lo-

A gun fires a bullet vertically into a 1.40-kg block of wood at rest on a thin horizontal 1.40 kg sheet, Fig. 7–44. If the bullet has a mass of 25.0 g and a speed of 230 m/s, how high will the block rise into the air after δυ=230 m/s the bullet becomes embedded in it? FIGURE 7-44 Problem 72.

A bowling ball hangs from a 1.0-m-long cord, Fig. 7–30: (i) A 200-gram putty ball moving 5.0 m/s hits the bowling ball and sticks to it, causing the bowling ball to swing up; (ii) a 200-gram rubber ball moving 5.0 m/s hits the bowling ball and bounces straight back at nearly 5.0 m/s, causing the bowling ball to swing up. Describe what happens. (a) The bowling ball swings up by the same amount in both (i) and (ii). (b) The ball swings up farther in (i) than in (ii). (c) The ball swings up farther in (ii) than in (i). (d) Not enough information is given; we need the contact time between the rubber ball and the bowling ball. (i) (ii)

A 900-kg small car slows down to 20.0 km/h to read a road sign. A 2400-kg passenger van following the small car fails to see that the small car has slowed and continues traveling at 70.0 km/h. The passenger van slams into the small car. Assume both vehicles are traveling in the same positive direction. (i) With what velocity will the two vehicles move if they lock bumpers after the rear-end collision? (ii) Find the change in the kinetic energy of the system consisting of both vehicles.

15-130. Sand drops onto the 2-Mg empty rail car at 50 kg/s from a conveyor belt. If the car is initially coasting at 4 m/s, determine the speed of the car as a function of time. 4 m/s