Iam one of the most dynamic processes of earth. i recycle earth's materials. i move earth's crustal plates, creating many different geological surface features. i am also the cause of natural disasters, such as earthquakes and volcanoes. what am i?

20. threshold braking in the vehicle's braking system occurs when a. the brake pedal is pushed, heel on floorboard, with full foot pressure. b. the brakes are exerting full braking power, without traction loss. c. the driver begins pushing down the brake pedal, with moderate slowdown. d. the brakes just begin to take hold with a gradual slowdown.

Given the position vector of the particle r(t)=(t+1)i+(t^2−1)j+2t k, find the particle's velocity and acceleration vectors at t=1

Why don't you see your reflection in water with waves or repples