Answer:
The correct option is (C).
Explanation:
Electric current can be direct or alternating.
The direct current flows only in one direction. It is unidirectional.
The alternating current or an C current reverse its direction periodically.
So, the correct statement regarding the alternating current is (c) i.e. Electrons reverse direction periodically.
Answer: To find the atomic mass of an atom of an element, add up the mass of protons and neutrons.
Explanation: Find the atomic mass of an isotope of carbon that has 7 neutrons. You can see from the periodic table that carbon has an atomic number of 6, which is its number of protons.
Answer:
Explanation:
<em>Assuming the triangle is a right triangle,</em>
the magnitude of R can be found using the Pythagorean theorem,
R = sqrt(9.7^2+6^2) = 11.41 m
The angle can be found by arctangent, which is
angle = atan(9.7/6) = 58.26 degrees.
Answer:
15.67 m/s
Explanation:
The ball has a projectile motion, with a horizontal uniform motion with constant speed and a vertical accelerated motion with constant acceleration g=9.8 m/s^2 downward.
Let's consider the vertical motion only first: the vertical distance covered by the ball, which is S=50 m, is given by

where t is the time of the fall. Substituting S=50 m and re-arranging the equation, we can find t:

Now we now that the ball must cover a distance of 50 meters horizontally during this time, in order to fall inside the carriage; therefore, the velocity of the carriage should be:
