As we know that time period of simple pendulum is given as
T = 2π √L/g
here we know that
T = 3.8 s
now from above equation we know that
T² = 4π² (L/g)
now on rearranging the above equation we will have
L = gT² / 4π²
now plug in all data into it
L = (9.8) (3.8)² / (4) (3.14)²
so the length of the cable must be 3.6 m
We are given a series circuit with two light bulbs. In this case, the light bulbs act as resistors in series and the total resistance is:

That is the sum of all the resistances in series in the circuit. To determine the voltage we can use Ohm's law:

Where "R" is the total resistance and "I" is the current in the circuit. Replacing we get:
Kinetic energy because of the wood plank is just still and not moving it’s potential but since it’s asking which one it doesn’t have it doesn’t have kinetic energy cause it’s not moving
True: Friction depends on the types of surfaces involved and how hard the surfaces push together.
The answer here is prism. The light passing through prism experiences bending of its multiple wavelength composition which allows it to visibly shows the difference in each of the light's color wavelength, violet bending the most while the least is the color red.