A 50 kg student stands on a 4 kg skateboard at rest. The student catches a 9 kg backpack moving with a horizontal speed of 2 m/s in the direction the skateboard is free to roll. How fast will the student and the skateboard move after catching the backpack, assuming friction is negligible? Round your final answer to the hundredths place.​

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.)

Ahockey puck sliding along frictionless ice with speed v to the right collides with a horizontal spring and compresses it by 3.0 cm before coming to a momentary stop.

Gravity is pulling an object into the sun. the closer the object gets to the sun, the greater the gravitational force that acts on the object, increasing its acceleration. a line graph plotting the speed of the object against time would have which shape? a: straight line of positive slope b: curved line that slopes upward c: curved line that slopes downward d: straight line of negative slope