When the cornea and lens of the eye do not properly focus light onto the retina, corrective lenses are needed. When are concave lenses
appropriate for vision correction?

Aboy with a mass 25 kg climbs into a small tree. he sits on a branch that is 2.o m above to the ground.what is his gravitational potential energy above the ground?

Two cannon balls weighing 18 kg and 24 kg are chained together and fired horizontally with a velocity of 165 m/s from the top of a 21-m wall. the chain breaks during the flight of the cannonballs and the 18-kg cannonball strikes the ground at t = 1.5 s, at a distance of 240 m from the foot of the wall, and 7 m to the right of the line of fire. determine the position of the other cannonball at that instant. neglect the resistance of the air.

Orque can be calculated by multiplying the force (n) applied at 90∘ to the lever arm at a distance (m) from the pivot point (point of rotation), the compound si unit for the torque is n⋅m. if the force (at 90∘ to the lever arm) applied is 15 n and it is applied at 2.0 m from the pivot point (point of rotation), what is the torque on the lever?