The helium used to fill birthday balloons doesn’t come out of the air, but from. out of the ground. some of the gas might escape from the ground into the. atmosphere, but the majority of it is trapped in earth’s crust. based on what you have learned from the experiment, give a reasonable explanation for the presence of helium gas in earth’s crust.

The focal length of a relaxed human eye is approximately 1.7 cm. when we focus our eyes on a close up object, we can change the refractive power of the eye by about 16 diopters. (a) does the refractive power of our eyes increase or decrease by 16 diopters when we focus closely? explain. (b) calculate the focal length of the eye when we focus closely.

Which of the following is an example of motion in two dimensions?

Which statement best describes the direction of the buoyant force on any object? a. opposite the force of gravity b. in the same direction as the weight c. in the direction of motion of the object d. opposite the direction of motion of the object