You want to lift a heavy box with a mass L = 56.0 kg using the two-ideal pulley system as shown. With what minimum force do you
1 answer:
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Explanation:
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Answer:
a) 230 Km b) 76.7 km/h c) Please see below
Explanation:
a) If we can neglect the time while the driver accelerated, the movement can be divided in two parts, each of them at a constant speed:
⇒
b) The average x component of velocity, can be calculated applying the definition of average velocity, as follows:
If we choose t₀ = 0 and x₀ = 0, replacing xf and t by the values we have already found, we can find vavg,x as follows:
c) The found value of avg,x is not the same as the arithmetic average of the initial and final values of vx (70 Km/h) due to the time traveled at both velocities was not the same.
If the driver had droven half of the time (1.5 h) at 50 km/h and the other half at 90 km/h, total displacement would have been as follows:
Applying the definition of average velocity once more:
which is the same as the arithmetic average of the initial and final values of vₓ.
Initially there were 10 bulbs of 60 Watt power
So total power of all bulbs = 60 * 10 = 600 W
now each bulb used for 4 hours daily
so total energy consumed daily
E = p*t
E = 600*4 = 2400Wh
E = 2.4kWH
now we have total power consumed in 1 year
E = 365 * 2.4 = 876kWh
cost of electricity = 10 cents/ kWh
so total cost of energy for one year
P1 = 876*10 = 8760cents = 87.60
Now if all 60 Watt bulbs are replaced by 30 Watt bulbs
So total power of all bulbs = 30 * 10 = 300 W
now each bulb used for 4 hours daily
so total energy consumed daily
(The next steps are in the pic.)
