3questions, 10 points a question, will give brainliest.
question 1: in which of these situations, is mechanical energy being conserved? (neglect, air resistance, friction and breaking) check all that apply.
question 1 options:

child on a swing

pendulum

bow and arrow

roller coaster

question 2: as an object falls to the ground, its potential energy is being converted to kinetic energy.

question 2 options:
true
false

question 3: calculate the potential energy stored in a 10 kg block, 5 meters above the ground.

question 3 options:

490 j

50 j

490 n

50 n

Why is metal often used for cooking pan?

Cathy is pedaling down a steep hill on her bicycle and wants to be able to coast up the next hill, which is 25 meters high, without pedaling. cathy and her bicycle have a mass of 75 kg. assuming her bicycle is 100% efficient, what would her speed have to be?

People with normal vision cannot focus their eyes underwater if they aren't wearing a face mask or goggles and there is water in contact with their eyes. in a simplified model of the human eye, the aqueous and vitreous humors and the lens all have a refractive index of 1.40, and all the refraction occurs at the cornea, whose vertex is 2.60 cm from the retina.with the simplified model of the eye, what corrective lens (specified by focal length as measured in air) would be needed to enable a person underwater to focus an infinitely distant object? (be careful-the focal length of a lens underwater is not the same as in air! assume that the corrective lens has a refractive index of 1.62 and that the lens is used in eyeglasses, not goggles, so there is water on both sides of the lens. assume that the eyeglasses are 2.05cm in front of the eye.)