Answer:
$ 1.1
Explanation:
From the question given above, the following data were obtained:
Cost per kWh = $ 0.1
Current (I) = 10 A
Voltage (V) = 220 V
Time (t) = 5 h
Cost of operation =?
Next, we shall determine the power the electric oven. This can be obtained as follow:
Current (I) = 10 A
Voltage = 220 V
Power (P) =?
P = IV
P = 10 × 220
P = 2200 W
Next, we shall convert 2200 W to KW. This can be obtained as follow:
1000 W = 1 KW
Therefore,
2200 W = 2200 W × 1 KW / 1000 W
2200 W = 2.2 KW
Thus, 2200 W is equivalent to 2.2 KW.
Next, we shall determine the energy consumed by the electric oven. This can be obtained as follow:
Power (P) = 2.2 KW
Time (t) = 5 h
Energy (E) =?
E = Pt
E = 2.2 × 5
E = 11 KWh
Finally, we shall determine the cost of operation. This can be obtained as follow:
1 KWh cost $ 0.1
Therefore,
11 KWh will cost = 11 × 0.1
11 KWh will cost = $ 1.1
Therefore, the cost of operating the electric oven is $ 1.1
Average speed = (total distance covered) / (time to cover the distance)
Total distance = (80m) + (125m) + (45m) = 250 meters
Overall time = 10 minutes
Average speed = (250 meters) / (10 minutes)
<em>Average speed = 25 meters/minute </em>
Since we're only looking for average speed and not velocity, we don't care about any of the directions, and we don't need to calculate Mary's displacement.
How much gravitational potential energy does the block have
when it gets to the top of the ramp ?
(weight) x (height) = (15 N) x (0.2 m) = 3 Joules .
If there were no friction, you would only need to do 3 Joules of work
to lift the block from the bottom to the top.
But the question says you actually have to do 4 Joules of work
to get the job done.
Friction stole one of your Joules along the way.
Choice-4 is not the correct one.
Choice-1 is the correct one.
===========================
Notice that the mass of the block is NOT 15 kg , and you
don't have to worry about gravity to answer this question.
The formula for potential energy is (m)·(g)·(h) .
But (m·g) is just the WEIGHT, and the formula
is actually (weight)·(height).
The question GIVES us the weight of the block . . . 15 N .
So the potential energy at the top is just (15N)·(0.2m) = 3 Joules.
