Answer:
The intensity of 4 lawn movers is 86 dB.
Explanation:
Intensity of one lawnmower = 80 dB
Let the intensity is I.
Use the formula of intensity
Now the intensity of 4 lawn movers is
Answer: T2 = 7.07s
Explanation: The period of a loaded spring of spring constant k and mass m is given by
T= 2π √m/k
With 2π constant and k, it can be seen with little algebra that
T² is proportional to mass m
Hence (T1)²/m1 = (T2) ²/m2
Where T1 = 5, T2 =?, let m1 = m hence m2 = 2m.
By substituting, we have that
5²/m = (T2) ²/2m
25 / m = (T2) ²/2m
25 × 2m = (T2) ² × m
25 × 2 = (T2) ²
50 = (T2) ²
T2 = √50
T2 = 7.07s
Answer:
Mass of natural gas needed to heat the room is 350,000BTUs
Explanation:
The heating efficiency of a furnace is never 100% because not all energy is released and not all heat is available to heat the place. A lesser efficiency requires more consumption of fuel. Heating values are used for heating fuels in order to calculate the mass of fuel needed.
The heating value of natural gas is 1,000,000BTUs
Therefore the formular for calculating mass of natural gas needed= Heating value of natural gas×efficiency.
Mass=1,000,000×0.35
Mass=350,000BTUs
Answer:
36 km/h
Explanation:
The total velocity is the sum of the two velocities that add to the movement of the boat.
Since the wind pushes the boat at 21 km/h and the current that runs in the direction of the movent of the boat is 15 km/h, the total velocity at wich the boat moves is:
21km/h + 15 km/h = 36 km/h
Because plastic and rubber are insulators.
