Answer:
Velocity v= 12.25 
Explanation:
The first rock dropped give the distance Y in meters

Now the motion of the second rock the time change so to know the velocity

Generally, the internal resistance of the new battery is small, about 0.2 euros, while the old battery is large, close to 1 euro ,
Answer:
OPTION A is the correct answer
I believe the answer would be 24N
Explanation: Because the forces are going against each other, in order to calculate the work done we need to subtract them. 47-23=24
Answer:
Atomic number of the daughter isotope = (Atomic number of the parent isotope) - 4
Explanation:
An alpha particle has atomic number of 2 and a mass number of 4
Losing two alpha particles would lead to a reduction of 4 in atomic number and 8 in mass number for the radioactive isotope, to give the stable daughter isotope.