Answer:
I believe the answer is A and D.
I am unsure of C.
Answer:
d = 100.8 ft
Explanation:
As we know that initial speed of the van is 40 miles then the stopping distance is given as 70 feet
here we know that

so here we have

now again if the speed is increased to 48 mph then let say the stopping distance is "d"
so we will have

now divide the above two equations


Answer: The chemical formula for the compound of these two elements is 
Explanation:
For formation of a neutral ionic compound, the charges on cation and anion must be balanced. The cation is formed by loss of electrons by metals and anions are formed by gain of electrons by non metals.
Here metal lead is having an oxidation state of +4 called as
cation and sulphur non metal has oxidation state of -2 called as
. Thus they combine and their oxidation states are exchanged and written in simplest whole number ratios to give neutral 
The chemical formula for the compound of these two elements is 
Answer:
Increase in mass and height
Explanation:
The gravitational potential energy of an object can increase if the mass and height of object is increased.
Gravitational potential energy is the energy due to the position of a body.
It is expressed as:
Gravitational potential energy = mass x acceleration due gravity x height
Increasing mass and height will cause an increase in gravitational potential energy.