Answer:
a) 
Explanation:
a) the cross-sectional area of the hose would be the square of radius times pi. And since the sectional radius is half of its diameter d. We can express the cross-sectional area A1 in term of diameter d1

Voltage is given by the formula
V = IR (Ohms law)
where V is the Voltage
I is the current
and R is the Resistance
Here it is given that the current is I=11
Resistance is R =12
so plugging this in the formula
V = IR
V= 11 * 12
V= 132 Volts
So the Voltage for the given dryer is 132 Volts
The mechanical energy of the roller coaster is sum of kinetic energy K and gravitational potential energy U:

where

is the kinetic energy

is the gravitational potential energy
Since the ride is frictionless, the total mechanical energy E is conserved during the ride. Therefore, at the top of the hill, the potential energy is maximum, because h (the height) is maximum, and this means the kinetic energy is minimum (because the sum of K and U is constant), so the velocity will be minimum. Viceversa, at the bottom of the hill, the potential energy will be minimum (because h is minimum), so the kinetic energy K will be maximum, and the velocity v of the roller coaster will be maximum.
Answer:
a = 1.666... m/s²
Explanation:
a = v2 - v1 / t2 - t1
a = 21m/s - 14m/s / 6s - 0s
a = 7m/s / 6s
a = 1.666... m/s²