Answer:
The constant force exerted on the ball by the wall is 119.68 N.
Step-by-step explanation:
Consider the provided information.
It is given that the mass of the ball is m = 2.2 kg
The initial velocity of the ball towards left is 7.4 m/s
So the momentum of the ball when it strikes is = 
The final velocity of the ball is -6.2 m/s
So the momentum of the ball when it strikes back is = 
Thus change in moment is: 
The duration of force exerted on the ball t = 0.25 s
Therefore, the constant force exerted on the ball by the wall is:

Hence, the constant force exerted on the ball by the wall is 119.68 N.
Answer:
62%
Step-by-step explanation:
The amount of substance left of a radioactive element of half life,

after a time, t, is given by:

Given that <span>potassium-40 has a half life of approximately 1.25 billion
years.
The number of years it will take for 0.1% of potassium-40 to remain is obtained as follows:

Therefore, </span><span>the maximum age of a fossil that we could date using 40k is
12.5 billion years.</span>