Which of these questions is a scientific question about skateboarding?
a how fast does a skateboard move at the bottom of a ramp?
b. which color of wheel looks best?
c. should skateboarding be allowed in shopping malls?
d. what is the best trick to do while moving backward?

Acave rescue team lifts an injured spelunker directly upward and out of a sinkhole by means of a motor-driven cable. the lift is performed in three stages, each requiring a vertical distance of 10.0 m: (a) the initially stationary spelunker is accelerated to a speed of 4.90 m/s; (b) he is then lifted at the constant speed of 4.90 m/s; (c) finally he is decelerated to zero speed. how much work is done on the 68.0 kg rescue by the force lifting him during each stage?

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

Suppose you increase your walking speed from 7 m/s to 13 m/s in a period of 2 s. what is your acceleration?