Answer:
The weight of the person has a smaller magnitude.
Explanation:
For an observer in inertial frame of reference for the person in the elevator Newton's Second Law can be written as
Normal reaction acts upwards
Weight acts downwards
Here
N is the normal reaction force
mg is the weight of the person
g is acceleration due to gravity
Answer:
The rotational frequency must be 2073.56 rpm
Explanation:
Notice that we need to obtain a rotational frequency in "rpm" (revolutions per minute), so we better start by converting all the given information into the appropriate units:
The magnitude of the velocity for the pitch is given in miles per hour, while the diameter of the machine's wheels is given in cm. Let's reduce all units of length into meters(using the metric system), and the units of time into minutes.
Conversion of the 85 mph speed into meters per minute:
Recall that 1 mile equals 1609.34 meters, and that 1 hour equals 60 minutes, so we write:
which can be rounded to approximately 2280 m/min.
We also convert the 35 cm diameter into meters:
diameter = 0.35 m
Now we use the equation that relates angular velocity (w) and the radius (R) of the circular movement, with tangential velocity (), in order to obtain the angular velocity of the wheel:
but recall that this angular velocity is given in radians per unit of time. So first find the radius of the wheel (half its diameter). R = 0.175 m
So we have:
And now, recalling that radians equal one revolution, we convert the angular velocity ot revolutions per minute by dividing the "w" we found by
:
rotational frequency =
Answer: Volume of Freon = 12.23.L
Explanation: First, the temperatures have to be in the same unit, so all the tmeperatures is transformed into Kelvin:
T₁ = 192K
T₂ = . (F - 32)+273.15
T₂ = . (- 65 - 32)+273.15
T₂ = 219.26K.
Second, BTU is an unit of energy. It can be transformed into Joules by the relation 1BTU = 1055.06J.
Q = 1055.06 . 46.9 = 49482.314J
The letter Q represents Heat and is calculated as Q = m.Cp.ΔT, where:
m is mass of the element;
Cp is the heat capacity specific for each element;
ΔT is the difference between the final and initial temperature;
Third, it will be needed the properties of the Freon:
Freon (CF2Cl2) = 120.91g/mol; Cp = 74J/mol.K; ρ = 1.49kg/m³
Fourth, we calculate the mass of Freon necessary for the remove of 46.9BTU of energy from the system:
Q = m.Cp.ΔT
m=
m =
m = 18228.214g or m=18.228Kg
Fifth, using the density of Freon, Volume can be found
ρ =
V = m / ρ
V = 18.228 / 1.49
V = 12.23m³
As SI for density is Kg/m³, the volume found is in m³.
Cubic meters is related to Liters as the following: 1m³=1000l.
So, volume of Freon = 12.23.L
The volume of Freon needed is 12.23.L.
