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?

A How fast does a skateboard move at the bottom of a ramp?

Explanation:

How fast does a skateboard move at the bottom of a ramp is a scientific question about skateboarding.

'A' is the only one that can be tested and measured.

'B' and 'D' ask for 'best'. 'C' asks 'should'. These are things that can't be measured, and they're individual opinions anyway.

you cant move and you feel like someones pushing you down onto your bed it can feel like you want to get up but you just can't it can be extremely scary

a solenoid is created by wrapping a l = 90 m long wire around a hollow tube of diameter d = 4.5 cm.   the wire diameter is d = 0.9 mm.   the solenoid wire is then connected to a power supply so that a current of i = 9 a flows through the wire.

randomized variablesl = 90 m

d = 4.5 cm

d = 0.9 mm

i = 9 a                                          

write an expression for the number of turns, n, in the solenoid. you do not need to take into account the diameter of the wire in this calculation.

calculate the number of turns, n, in the solenoid.

write an expression for the length of the solenoid (l2) in terms of the diameter of the hollow tube d.

calculate the length of the solenoid (l2)   in meters.

calculate the magnitude of the magnetic field at the center of the solenoid in teslas.

explanation: