Answer:
The answer is D.
Explanation:
Look at these options. Do all of these require effort? Yes. If you were to push a shopping cart, do you have to apply force? if you were to lift a book, do you indeed move the book, does it exert force? While walking up stairs, do you have to move your legs uphill, is there force used? All of these require input, and force. Most things in life require work, unless we have a machine to do it for us.
Explanation:
Problem 2.5, mixing dough.
Please note dimensional units and standard formulas for energies.
Input:
Electrical energy = VIT = 110 V * 1.5 A * 5 min. * 60 s/min = 49500 joules = 49.5 kJ
Output:
Warming of dough = mCΔT = 1 kg * 4.2 kJ/(kg*K) * 5 deg.K = 21 kJ
Dissipation of energy = remainder of input energy = (49.5-21) kJ = 28.5 kJ
Fraction of energy converted to energy of dough = 21 kJ / 49.5 kJ
= forty-two percent (to the nearest percent)
The last item, dissipation of energy could be attributed to:
1. Loss in efficiency of mixer in the form of mechanical friction, heating up due to resistance of motor circuit, etc.
2. Loss in mechanical mixing of dough due to friction between mixer paddle and dough in the form of heat, part of which stays with dough (thus heating up of dough), and the remainder heats up the dough container, loss of heat to environment, air, heat of vaporization of water content of dough, etc.
Answer: same
Explanation: They both weigh a kilogram and there is no friction
Time= 20 minutes= 20*60=1200 s
Charge=current*time=12*1200=14400 C
Answer:
Explanation:
each grid corresponding 0.1s⁻¹.
0.2grid unit = 0.2×0.1 =0.02s⁻¹
distance of the star from telescope
d = 1/p
d= 1/0.02= 50 par sec
1par sec = 3.26 light year
1 light year = 9.5×10¹²km
3.26ly=3.084×10¹³km
d= 50×3.084×10¹³=1.55×10¹⁵km