If both particles have the SAME electrical charge, then they repel.
If they have DIFFERENT electrical charge, then they attract.
Protons have + charge .
Electrons have - charge .
So two protons (A) or two electrons (D) push apart.
One proton and one electron (C) pull together.
The atomic number of an element is the number of protons the element has, so the element with the atomic number 55 has 55 protons.
Answer:
The block's mass should be 
Explanation:
Given:
Cart with mass 
From the conservation of energy before mass is added,
Where 
amplitude of spring mass system, 
spring constant
Now new mass 
is added to the system,
Here, given in question frequency is reduced to half so we can write,
Where 
frequency of system before mass is added, 
frequency of system after mass is added.
Therefore, the block's mass should be
Answer:
increased with the same rate as momentum
Answer:
an object sliding down hill
Explanation:
On a slope, the force applied is due to gravity. Its direction is straight down. If the object is sliding down the hill, its displacement is at an angle to the applied force. The angle of displacement will depend on the steepness of the hill.
