9. Hikers at the bottom of a canyon are facing towards the canyon wall 280.5 meters away. Given that the speed of sound in air is 340 m/s, how long after they shout will they hear their echo?

The ultracentrifuge is an important tool for separating and analyzing proteins. because of the enormous centripetal accelerations, the centrifuge must be carefully balanced, with each sample matched by a sample of identical mass on the opposite side. any difference in the masses of opposing samples creates a net force on the shaft of the rotor, potentially leading to a catastrophic failure of the apparatus. suppose a scientist makes a slight error in sample preparation and one sample has a mass 10 mg larger than the opposing sample. if the samples are 12 cm from the axis of the rotor and the ultracentrifuge spins at 70,000 rpm, what is the magnitude of the net force on the rotor due to the unbalanced samples? ( be thorough on your answer)

An airplane is flying with a velocity of 240 m/s at an angle of 30.0∘ with the horizontal, as the drawing shows. when the altitude of the plane is 2.4km,a flare is released from the plane. the flare hits the target on the ground. what is the angle θ?

Hurry! how much heat is absorbed by a 72g iron skillet when its temperature rises from 11°c to 23°c?