Round each of the following to 3 significant figures.
1 answer:
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Answer:
cost of running the furnace during January is $5619.62
Explanation:
given data
runs a day = 13 hours
January days = 31 days
resistance = 7.2 ohm
current = 16.7 A
cost of electricity = $0.10/kWh
to find out
cost of running the furnace during January
solution
first we get her power consumed by furnace that is
Power consumed = ........1
put here value we get
Power consumed =
Power consumed = 38.7347 W
and
Power consumed by furnace in one hour is
Power consumed by furnace in one hour is = Power consumed × 3600
Power consumed by furnace in one hour is = 38.7347 × 3600
Power consumed by furnace in one hour is 139.445kWh
and
Power consumed by furnace in the month of January is
Power consumed by furnace in the month of January = 139.445kWh × 13 hours × 31 days
Power consumed by furnace in the month of January = 56196.335 kWh
so
cost of running the furnace during January is = $0.10/kWh × 56196.335 kWh
cost of running the furnace during January is $5619.62
Answer:
The velocity of the skateboard is 0.774 m/s.
Explanation:
Given that,
The spring constant of the spring, k = 3086 N/m
The spring is stretched 18 cm or 0.18 m
Mass of the student, m = 100 kg
Potential energy of the spring,
To find,
The velocity of the car.
Solution,
It is a case of conservation of energy. The total energy of the system remains conserved. So,
v = 0.774 m/s
So, the velocity of the skateboard is 0.774 m/s.
The thermal efficiency of an engine is
where
W is the work done by the engine
Q is the heat absorbed by the engine to do the work
In this problem, the work done by the engine is W=200 J, while the heat exhausted is Q=600 J, so the efficiency of the machine is
where
W is the work done by the engine
Q is the heat absorbed by the engine to do the work
In this problem, the work done by the engine is W=200 J, while the heat exhausted is Q=600 J, so the efficiency of the machine is