Answer:
Net force due to all on the refrigerator is 400 N
Explanation:
As we know that two people are pushing the refrigerator while other two people are lifting the refrigerator
So net push force on the refrigerator is given as
Similarly net lift force on the refrigerator is given as
Now net force on the refrigerator is given as
Answer:
1353.38 Watt
Explanation:
T₁ = Initial temperature of the house = 35°C
T₂ = Final temperature of the house = 20°C
Δt = Time taken to cool the house = 38 min = 38×60 = 2280 s
m = mass of air in the house = 800 kg
Cv = Specific heat at constant volume = 0.72 kJ/kgK
Cp = Specific heat at constant pressure = 1.0 kJ/kgK
Heat removed
q = mCvΔT
⇒q = 800×720×(35-20)
⇒q = 8640000 J
Average rate of hear removal
∴ Power drawn by the air conditioner is 1353.38 Watt
Answer:
(a) The parachutist spent 24.84 secs in air
(b) The height the fall begins is 472 m
Explanation:
Here is the complete question:
A parachutist bails out and freely falls 63 m. Then the parachute opens, and thereafter she decelerates at 1.5 m/s2. She reaches the ground with a speed of 3.3 m/s. (a) How long is the parachutist in the air (b) At what height does the fall begin?
Explanation:
From one of the equations of kinematics for free fall
Where H is the height
u is the initial velocity
t is the time
and g is the acceleration due to gravity (Take g = 9.8 m/s2)
Now, we can find the time spent before the parachute opens.
u = 0 m/s (we assume the parachutist starts from rest)
H = - 63 m
∴
This the time spent before the parachute opens
Also from one of the equations of kinematics for free fall
where v is the final velocity
We can determine the final velocity before the parachute opens and she starts to decelerate
∴
Now, we will calculate the time spent after the parachute opens
From one of the equation of kinematics for linear motion,
Here, the initial velocity will be the final velocity just before the parachute opens, that is
From the question,
We then get
(a) To determine how long the parachutist is in the air,
That is sum of the time used when falling freely and the time used after the parachute opens
= 3.59 secs + 21.25 secs
24.84 secs
Hence, the parachutist spent 24.84 secs in air
(b) To determine what height the fall begins
First, we will calculate the height from which the parachute opens
From one of the equation of kinematics for linear motion,
≅
Hence, the height the fall begins is 63m + 409m
= 472 m
