Answer:
After a nucleus with 85 protons undergoes alpha decay, it has 83 protons.
Explanation:
In an alpha particle there are two protons
In the given substance's nucleus, there are total of 85 protons
After the decay, the proton number reduce
The current proton number after decay is
85 -2 = 83
After a nucleus with 85 protons undergoes alpha decay, it has 83 protons.
The speed of the car at the bottom of the hill is obtained as, 
According the principle of conservation of energy, the total potential energy of the car will be converted to maximum kinetic energy when the car is at the bottom of the hill.

where;
- <em>v </em><em>is the speed of the car at the bottom of the hill</em>
- <em>h </em><em>is the height of the hill</em>
- <em>g </em><em>is acceleration due to gravity</em>
Thus, the speed of the car at the bottom of the hill is obtained as, 
Learn more about conservation mechanical energy here: brainly.com/question/332163
No because the whether changes constant, weather can be close but is not the 100% the correct answer,..
Answer:
2697.75N/m
Explanation:
Step one
This problem bothers on energy stored in a spring.
Step two
Given data
Compression x= 2cm
To meter = 2/100= 0.02m
Mass m= 0.01kg
Height h= 5.5m
K=?
Let us assume g= 9.81m/s²
Step three
According to the principle of conservation of energy
We know that the the energy stored in a spring is
E= 1/2kx²
1/2kx²= mgh
Making k subject of formula we have
kx²= 2mgh
k= 2mgh/x²
k= (2*0.01*9.81*5.5)/0.02²
k= 1.0791/0.0004
k= 2697.75N/m
Hence the spring constant k is 2697.75N/m
The answer to your question is SPEED.