Answer:
200 N
Explanation:
Power = work / time
Work = force × distance
Therefore:
Power = force × distance / time
100 W = F × 10 m / 20 s
F = 200 N
He exerted 200 N.
Double
Explanation:
Since the period T of a pendulum is given by

By increasing the length of the pendulum by 4, the period becomes

You can see that the period doubles when we increase the length by a factor of 4.
Answer: B.
Capacitors prevent current from moving through a circuit
Explanation:
If a direct voltage is applied on the capacitor, no conduction current flows through the capacitor if its insulating medium is perfect insulator. This is due to the fact that there are no free charge carriers in such medium. Basically the real insulator contains very few charge carriers and therefore a very small leakage current passes in the capacitor depending on the conductivity of the insulator.
If an alternating voltage is applied on the capacitor, a displacement current passes through the capacitor irrespective of the insulating medium. This current is termed also the capacitive current. It flows because of changing electric displacement with time.
Answer:
A title
Explanation:
Because this is middle school.