Answer:
c. 70 Ω
Explanation:
The R and R resistors are in parallel. The 2R and 2R resistors are in parallel. The 4R and 4R resistors are in parallel. Each parallel combination is in series with each other. Therefore, the equivalent resistance is:
Req = 1/(1/R + 1/R) + 1/(1/2R + 1/2R) + 1/(1/4R + 1/4R)
Req = R/2 + 2R/2 + 4R/2
Req = 3.5R
Req = 70Ω
Answer:
c.
Explanation:
Electromagnetic waves are waves that are generated when an electric field and a magnetic field vibrate together. They are usually created whenever an electric field collides with a magnetic field.
In more generic terms for an electric field, the energy per unit volume is given by:
Energy density = 
For magnetic field:
Energy density =
∴
For the electromagnetic wave (u):
Total energy density is:

Due to the fact that the energy related with both fields is equivalent:
Then:
E = cB
Answer:
i think the answer is letter c
F=ma, so a=F/m. Thus, the more massive object accelerates more slowly, that is, the 21 kg object is three times slower than the 7 kg one (2nd variant, 7kg is 3 times faster than 21kg)
Answer:
The car moving with constant speed on the path with a deep curve experiences an acceleration towards the center of the curve.
Explanation:
Acceleration is the rate of change of velocity with time. A velocity has both magnitude and direction, and a change in either or both of the magnitude and the direction can produce an acceleration on the car. The car on the curved path experiences a change in the direction of travel along the path. This changes in direction at every point on the curve puts an acceleration on the car towards the center of the curve.