Answer:
(a)

(b)
1120 N
Explanation:
Change in velocity,
is given by subtracting the initial velocity from the final velocity and expressed as 
Where v represent the velocity and subscripts f and i represent final and initial respectively. Since the ball finally comes to rest, its final velocity is zero. Substituting 0 for final velocity and the given figure of 8 m/s for initial velocity then the change in velocity is given by

To find
then we substitute 7 kg for m and -8 m/s for
therefore 
(b)
The impact force, F is given as the product of mass and acceleration. Here, acceleration is given by dividing the change in velocity by time ie

Substituting t with 0.05 s then 
Since F=ma then substituting m with 7 Kg we get that F=7*-160=-1120 N
Therefore, the impact force is equivalent to 1120 N
I am very sorry I don’t know
The height risen by water in the bell after enough time has passed for the air to reach thermal equilibrium is 3.8 m.
<h3>Pressure and temperature at equilibrium </h3>
The relationship between pressure and temperature can be used to determine the height risen by the water.

where;
- V₁ = AL
- V₂ = A(L - y)
- P₁ = Pa
- P₂ = Pa + ρgh
- T₁ = 20⁰C = 293 K
- T₂ = 10⁰ C = 283 k

Thus, the height risen by water in the bell after enough time has passed for the air to reach thermal equilibrium is 3.8 m.
The complete question is below:
A diving bell is a 4.2 m -tall cylinder closed at the upper end but open at the lower end. The temperature of the air in the bell is 20 °C. The bell is lowered into the ocean until its lower end is 100 m deep. The temperature at that depth is 10°C. How high does the water rise in the bell after enough time has passed for the air to reach thermal equilibrium?
Learn more about thermal equilibrium here: brainly.com/question/9459470
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Answer: B. I hope you get this right.
Answer:
v= 335 m/s
2∆t= 0.75 s
∆x= v.∆t → ∆x= 335×½×0.75 = 125.625 m