Reflection- looking at yourself in a mirror and seeing the moon in the sky
Refraction- putting on your glasses in order to see more clearly and the pencil looks like it’s bent when you stick one end of it in water.
In gasoline powered boats, it is important to keep in mind the proper procedures in handling before activating the engine or your boat. Such as activating the blower. In activating the blower, it is advisable to turn it on after minutes of refueling and the engine should be activated afterwards. It is important to keep in mind to wait for a couple of minutes before turning it on because gasoline powered boats if not used or handled properly could cause harm such as explosion for it uses gasoline.
First you see the difference in mass numbers 238-234 = 4
Its is an alpha particle as it decreases the mass no by 4 .
Answer:
a) t = 3.2 s
b) 
Explanation:
a) El tiempo requerido para llegar al suelo se puede calcular usando la siguiente fórmula:

En donde:
: es la altura inicial = 50 m
g: es la gravedad = 10 m/s²

Entonces, el tiempo requerido para llegar al suelo es 3.2 s.
b) La rapidez de la pelota justo antes del choque es el siguiente:

En donde:
: es la velocidad inicial = 0 (dado que se deja caer en resposo)

Por lo tanto, la rapidez de la pelota justo en el momento anterior del choque es -32 m/s (el signo negativo es porque la pelota está cayendo).
Espero que te sea de utilidad!