In which of the following reactions or decays is strangeness conserved? In each case, explain your reasoning.
(a) $K^{+}+{\mu }^{+}+{\nu }_{\mu }$
(b) $n+K^{+}\to p+{\pi }^0$
(c) $K^{+}+K^{-}\to {\pi }^0+{\pi }^0$
(d) $p+K^{-}\to {\Lambda }^0+{\pi }^0$

In one day, a $75$-kg mountain climber ascends from the $1500$-m level on a vertical cliff to the top at $2400$ m. The next day, she descends from the top to the base of the cliff, which is at an elevation of $1350$ m. What is her change in gravitational potential energy on the first day?

A 12 kg weather rocket generates a thrust of 200 N. The rocket, pointing upward, is clamped to the top of a vertical spring. The bottom of the spring, whose spring constant is 550 N/m, is anchored to the ground. After the engine is ignited, what is the rocket’s speed when the spring has stretched 40 cm?

Sketch the n = 8 wave function for the potential energy shown in FIGURE EX40.13.

In the high jump, the kinetic energy of an athlete is transformed into gravitational potential energy without the aid of a pole. With what minimum speed must the athlete leave the ground in order to lift his center of mass 2.10 m and cross the bar with a speed of 0.50 m/s?

A novice skier, starting from rest, slides down an icy frictionless 8.0° incline whose vertical height is 115 m. How fast is she going when she reaches the bottom?

A sled is initially given a shove up a frictionless 18.0° incline. It reaches a maximum vertical height 1.22 m higher than where it started at the bottom. What was its initial speed?