A) current
(I is always current in electricity)
The variable that changes is the period of the motion.
<h3>What is simple harmonic motion?</h3>
The term simple harmonic motion refers to a regular repeating motion. The acceleration of the SHM is always directed towards the center. The spring is an example of a system undergoing simple harmonic motion.
From the description in the question, the variable that changes is the period of the motion.
Learn more about simple harmonic motion: brainly.com/question/17315536
Answer:
It attracts ferrous materials
Explanation:
A magnet attracts ferrous materials A ferrous materials are metallic substances or conductors that can conduct heat and electricity. Example of this ferrous materials includes iron, metal etc. Since magnets only can attracts metallic substance to itself, then we can also conclude that they attract ferrous materials since ferrous materials. possesses properties of a metal.
Magnets possesses both north and south poles.
The same of the bar magnets are known to repel each other while unlike poles attract each other.
Answer:
Change in potential energy = 7350 Joules
Explanation:
It is given that,
Side of cube, a = 0.5 m
Density of cube, 
The cube is lifted vertically by a crane to a height of 3 m
We know that, density 
So, m = d × V (V = volume of cube = a³)

m = 250 kg
We have to find the change in potential energy of the cube. At ground level, the potential energy is equal to 0.
Potential energy at height h is given by :

PE = 250 kg × 9.8 m/s² ×3 m
PE = 7350 Joules
So, change in potential energy of the cube is 7350 Joules.
The kinetic energy K given to the helium nucleus is equal to its potential energy, which is

where q=2e is the charge of the helium nucleus, and

is the potential difference applied to it.
Since we know the kinetic energy, we have

and from this we can find the potential difference: