To solve this problem we will apply the definition of Newton's second law, which says that force is equivalent to body mass by acceleration. In this case the mass of the trailer is 325Kg and its acceleration is 
, so we will proceed to replace and multiply these values to find the net force on this object.
F= 698.75N
Under the reference system in which the direction of travel is the positive direction, the direction of the force will be positive.
D = 1/f, where D is the power in diopters and f is the focal length in meters.
D=1/20
<u>D=0.05</u>
Answer:
The current lags the potential difference by π/2 in an inductor
Explanation:
The potential difference leads to the current by 
. Alternate signals such as current and voltage -in this case- are periodic, this means that this signals are repeated at fixed spaces of time. Thus, In an inductor the current lags the potential difference by .
If it produces 20J of light energy in a second, then that 20J is the 10% of the supply that becomes useful output.
20 J/s = 10% of Supply
20 J/s = (0.1) x (Supply)
Divide each side by 0.1:
Supply = (20 J/s) / (0.1)
<em>Supply = 200 J/s </em>(200 watts)
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Here's something to think about: What could you do to make the lamp more efficient ? Answer: Use it for a heater !
If you use it for a heater, then the HEAT is the 'useful' part, and the light is the part that you really don't care about. Suddenly ... bada-boom ... the lamp is 90% efficient !
