As per energy conservation in the reversible engine we can say
here we know that
now from above equation
now we can convert it into kW
so above is the power input to the refrigerator
now to find COP we know that
so COP of refrigerator is 2.2
A force of 150 N accelerates a 25 kg wooden chair across a wood floor at 4.3 m/s2 . How big is the frictional force on the block
1 answer:
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Answer:
A: 4 times as much
B: 200 N/m
C: 5000 N
D: 84,8 J
Explanation:
A.
In the first question, we have to caculate the constant of the spring with this equation:
Getting the k:
Then we can calculate how much the spring stretch whith the another mass of 0,2kg:
The energy of a spring:
For the first case:
For the second case:
If you take the relation E2/E1 = 4.
B.
We have the next facts:
x=0,005 m
E = 0,0025 J
Using the energy equation for a spring:
⇒
C.
The potential energy of the diver will be equal to the kinetic energy in the moment befover hitting the watter.
Watch out the units in this case, the 500 N reffer to the weighs of the diver almost relative to the earth, thats equal to m*g.
D.
The work is equal to the force acting in the direction of the motion. so we have to do the diference beetwen angles to obtain the effective angle where the force is acting: 47-15=32 degree.
The force acting in the direction of the ramp will be the projection of the force in the ramp, equal to F*cos(32). The work will be:
W=F*d=F*cos(32)*d=10N*cos(32)*10m=84,8J