-- While gaining 2.15 m/s more speed every second, the van
would gain (2.15 x 7) = 15.05 m/s more speed in 7 seconds.
-- We're told that its speed at the end of the 7 seconds
is 20 m/s .
-- So its speed at the beginning of the 7 seconds must have been
(20 m/s - 15.05 m/s) = 4.95 m/s .
Answer:
72J
Explanation:
distance moved is equal to 3m.then just substitute x with 3m.
Fx = (14(3) - 3.0(3)2)) N
Fx =(42-18)N
Fx =24N
W=Fx *S
W=24N*3m
W=72J
Both the answers from "Big D" and "N9KXF" are correct, but not complete. There is one aspect that needs to be remembered for AC power - the phase relationship between the voltage and current.
<span>For AC power, the more complete equation for power is P = V * I * cosx, where x is the phase angle between voltage and current. </span>
<span>If the phase angle between voltage and current is 90 degrees, then even though current may be flowing, the total power over a cycle would be zero. Reactive elements like inductors and capacitors have a 90degree phase relationship between voltage and current. They do not "dissipate" energy. They store energy and give it back during different parts of the AC cycle. </span>