A little boy is standing at the edge of a cliff 1000 m high. He throws a ball straight downward at an initial speed of 20 m/s, and it falls straight down to the ground below.
A) At a time of 6 seconds after it was thrown, how far above the ground is it?
The acceleration due to gravity is 10 m/s^2

700 m

Explanation:

Using the equations of motion,

g = 10 m/s², H = 1000 m,

Initial velocity, u = 20 m/s,

final velocity, v = ?

Total Time of fall, t = ?

a) But at t = 6s, g = 10 m/s², y = The height the ball has fallen through.

y = ut + gt²/2

y = (20×6) + 10(6²)/2

y = 300 m

Height of the ball above the ground at t = 6s is (Height of the cliff - height the ball has fallen through) = 1000 - 300 = 700 m

700 m.

Explanation:

Using equations of motion,

Given:

t = 6s

g = 10 m/s²y

S = vi*t + (g*t²)/2

= (20*6) + (10*6²)/2

= 300 m

Height above the ground = Height of the cliff - height of the motion

= 1000 - 300

= 700 m

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:

waves moving from a fast medium to a slow medium will experience a reflection as light travels more slowly than red light. total internal reflection occurs when the critical angle is.