Answer:
Simple machines are useful because they reduce effort or extend the ability of people to perform tasks beyond their normal capabilities. Simple machines that are widely used include the wheel and axle, pulley, inclined plane, screw, wedge and lever.
Answer:
D. n=6 to n=2
Explanation:
Given;
energy of emitted photon, E = 3.02 electron volts
The energy levels of a Hydrogen atom is given as; E = -E₀ /n²
where;
E₀ is the energy level of an electron in ground state = -13.6 eV
n is the energy level
From the equation above make n, the subject of the formula;
n² = -E₀ / E
n² = 13.6 eV / 3.02 eV
n² = 4.5
n = √4.5
n = 2
When electron moves from higher energy level to a lower energy level it emits photons;
For a photon to be emitted, electron must move from higher energy level to a lower energy level. The higher energy level is 6 while the lower energy level is 2
Therefore, The electron energy-level transition is from n = 6 to n = 2
Answer:
B. Gravitational force
Explanation:
The gravitational force of an object (also called weight) is given by
where m is the mass of the object and g is the acceleration of gravity, and it always points in the downward direction.
In this problem, the arrow labelled with 4 is the only force pointing downward: therefore, it must be the gravitational force.
The other arrows represent:
1 --> component of the gravitational force parallel to the plane
2 --> force of friction
3 --> component of the gravitational force perpendicular to the plane
Out of that list, the concave mirror is the only item that can concentrate sunlight and heat into a small area. But if you could get ahold of a convex lens, that would be even better.
Answer:
- Distance is a scalar quantity, defined as the total amount of space covered by an object while moving between the final position and the initial position. Therefore, it depends on the path the object has taken: the distance will be minimum if the object has travelled in a straight line, while it will be larger if the object has taken a non-straight path.
- Displacement is a vector quantity, whose magnitude is equal to the distance (measured in a straight line) between the final position and the initial position of the object. Therefore, the displacement does NOT depend on the path taken, but only on the initial and final point of the motion.
If the object has travelled in a straight path, then the displacement is equal to the distance. In all other cases, the distance is always larger than the displacement.
A particular case is when an object travel in a circular motion. Assuming the object completes one full circle, we have:
- The distance is the circumference of the circle
- The displacement is zero, because the final point corresponds to the initial point
