It can solidify, it depends on the tempeture.
Hi there!
The answer would be B. the slope of the plane.
Changing the slope of the plane would show how fast the ball went when Galileo changed the steepness of the slope. If he didn’t change the slopes steepness he would have the same results each time.
Hope this helps !
6. Since we are not sure if the person in the question is actively lifting the crate, we have to determine the downwards force of the crate due to gravity and compare it to the normal force.
F = ma
F = (15.3)(-9.8)
F = -150N
Since the downwards force of the crate is equivalent to the normal force, it means the person is applying no force in picking up the object. So to pick up a 150N object from scratch, you would have to exert more force than the weight of the object, so the answer is 294N.
7. Same idea as question 2.
First determine the weight of the object:
F = ma
F = (30)(-9.8)
F = -294N
The crate in question is not moving, so the magnitudes of the forces in the upwards and downwards direction has to equal to 0.
-294 + 150N + x = 0
x = 144N
So the person is exerting 144 N.
10. First find the force of block B to the right due to its acceleration:
F = ma
F = (24)(0.5)
F = 12N
So block B is moving 12N to the right relative to block A due to block A's movement to the left. However, block A is being applied a much greater force and is moving quicker to the left than block B is moving to the right of bock A. The force that is causing block B to experience the lower relative force to the right is because of the friction. To find the friction:
The sum of the forces in the leftward and rightward direction for block B must equal 12N.
75 - x = 12
x = 63N
So the force of friction of block A on block B is 63N to the left.
Answer: C) The two particles will move away from each other
Explanation:
When two electrically charged bodies come closer, appears a force that attracts or repels them, depending on the sign of the charges of this two bodies.
This is stated by Coulomb's Law:
"The electrostatic force 
between two point charges 
and 
is proportional to the product of the charges and inversely proportional to the square of the distance 
that separates them, and has the direction of the line that joins them"
Mathematically this law is written as:
Where 
is a proportionality constant.
Now, if and have the same sign charge (both positive or both negative), a repulsive force will act on these charges.
