How much does it cost to operate a 25-w soldering iron for 8.0 hours if energy costs 8.0¢/kwh?
1 answer:
The power P is defined as the energy E per unit of time t:
In our problem, the power is P=25 W and the total time is t=8.0h, so we can calculate the total energy used during this time:
The energy costs 8€ per each kwh, so we can write the following proportion:
where x is the price corresponding to 0.2 kWh. Solving the proportion we find x:
€
In our problem, the power is P=25 W and the total time is t=8.0h, so we can calculate the total energy used during this time:
The energy costs 8€ per each kwh, so we can write the following proportion:
where x is the price corresponding to 0.2 kWh. Solving the proportion we find x:
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Answer:
The value of R is .
(B) is correct option.
Explanation:
Given that,
In analyzing distances by apply ing the physics of gravitational forces, an astronomer has obtained the expression
We need to calculate this for value of R
So, The nearest option of the value of R is
Hence, The value of R is .
The Young modulus is given by:
where
F is the force applied
is the initial length of the wire
is the cross-sectional area of the wire
is the stretch of the wire
The wire in the problem stretches by
of its length, this means
We can also calculate the area of the wire; its radius is in fact half the diameter:
and so the area is
We know the force applied to the wire, F=20 N, so now we have everything to calculate the Young modulus:
where
F is the force applied
The wire in the problem stretches by
We can also calculate the area of the wire; its radius is in fact half the diameter:
and so the area is
We know the force applied to the wire, F=20 N, so now we have everything to calculate the Young modulus: