A competitive diver executes a double somersault with a twist from a platform. Her height above the water t seconds after leaving the board is given in feet by h = − 16 t 2 + 0 t + 16 How long does she have to complete her somersault before entering the water?

One second

Explanation:

Her height above water as function of time after leaving the board is:

When she enters the water the height above the board is zero so h(t)=0, using that on (1):

solving equation for t:

s

Mathematically there're in fact two possible values for t, -1 and 1 but because we're talking of time negative sign has no physical sense then we only use 1.

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:

answer: 2×10^-2kg

explanation: density= mass per volume

vol=mass/density

converting to s.i units we have;

3÷1000kg = 0.003

1.5÷100m = 0.15

0.003/0.15 = 0.02kg