Cancellation (destructive interference) occurs at superposition of a crest and a(n): crest trough node barrier

Aballoon is rising vertically upwards at a velocity of 10m/s. when it is at a height of 45m from the ground, a parachute bails out from it. after 3s he opens his parachute and decelerates ata a constant rate 5m/s. when. (a) what was the height of the parachutist above the ground when he opened his parachute? (b)how far is the parachutist from the balloon at t=3s? (c)with what velocity does the parachutist hit the ground? (d)after how long does the parachutist hit the ground after his exist from the balloon?

What is a transverse wave? how do the particles in the medium move in relation to the energy of the wave? does this wave require a medium?

When a person spins a bucket of water in a circle, the force acting on the bucket to keep the water inside is called