What frequency is received by a person watching an oncoming ambulance moving at 115 km/h and emitting a steady 753 Hz sound from
1 answer:
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Answer:
10 m/s
Explanation:
Kinetic energy= mv² where m is mass and v is velocity.
We have to make v the subject so we should rearrange the equation
K=mv²
v²= (use algebra)
v²= 7/0.5×0.140
v²=100
v=√100
v=10 m/s
We can confirm this by using the kinetic energy formula.
K=×0.140×10²
K= 7 J
Hence it is proved that velocity is 10 m/s
Answer:
t=20s
Explanation:
To solve this problem we must apply the first law of thermodynamics, which indicates that the energy that enters a system is the same that must come out, resulting in the following equation
For this problem we will assume that the water is in a liquid state, since it is a domestic refrigerator
q=m.cp.(T2-T1)
q=heat
m=mass of water =600g=0.6Kg
cp=
specific heat of water=4186J/kgK
T2=temperature in state 2=20°C
T1=temperature in state 1=0°C
solving:
q=(0.6)(4186)(20-0)=50232J
A refrigerator is a device that allows heat to be removed to an enclosure (Qin), by means of the input of an electrical energy (W) and the heat output (Qout), the coefficient of performance COP, allows to know the ratio between the heat removed ( Qin) and the added electrical power (W), the equation for the COP is
To solve this exercise we must know the value of the heat removed to the water (Qin)
solving for Qin
Qin=(COP)(Win)
Qin=(5)(500W)=2500W
finally we remember that the definition of power is the ratio of work over time
w=work
p=power=500w