As light from air to water to glass, it will refract. the best explanation for this would be

 Light travels at different speeds in different medium because of the varying densities.

Explanation: The reason for the straw to break at the water's surface is because of the process of refraction. Light travels at different speeds in different medium because of the varying densities.

The light travels from air to water and thus the difference in speed results in an apparent shift of the position of part of straw under water and thus the part appears broken. This phenomenon is called as refraction.

it becomes positively charged by charging it

note: the given question is incomplete.

complete question is given below.

which is an example of kinetic energy?

a. the energy stored in ethanol  

b. a hockey puck sliding across the ice  

c. a compressed spring  

d. a ball sitting at the top of a ramp

solution: the kinetic energy is the energy posses by the virtue of the motion of the object.

in the given options, a, c and d are the example of potential energy because it is the energy posses by the virtue of the rest of the object. but option b has the kinetic energy as the object is in motion.

hence, a hockey puck sliding across the ice   is the apex example of kinetic energy.

so, the option (b) a hockey puck sliding across the ice   is the correct option.