Answer:
The speed of the ball is 9.07 m/s.
Explanation:
Given that,
Mass of the lead ball, m = 55 kg
Height of the tower, h = 55 m
We need to find the speed of the ball it has traveled 4.20 m downward, x = 4.2 meters
The initial speed of the ball will be 0 as it was at rest initially. Let v is the speed of the ball after it has traveled 4.20 m downward. It is a case of equation of motion such that :


Here, a = g

v = 9.07 m/s
So, the speed of the ball is 9.07 m/s. Therefore, this is the required solution of given condition.
Answer : The de-Broglie wavelength of this electron, 
Explanation :
The formula used for kinetic energy is,
..........(1)
According to de-Broglie, the expression for wavelength is,

or,
...........(2)
Now put the equation (2) in equation (1), we get:
...........(3)
where,
= wavelength = ?
h = Planck's constant = 
m = mass of electron = 
K.E = kinetic energy = 
Now put all the given values in the above formula (3), we get:


conversion used : 
Therefore, the de-Broglie wavelength of this electron, 
Move the decimal three places to the left -> .0004702
<h2>
Answer:</h2>
105146 Pa
<h2>
Explanation:</h2>
1) We will make a Free-Body Diagram representing all the upward and downward pressures exerted on the piston.
- Pressure exerted by the compressed spring (Pspring)
- Pressure due to weight of the piston (Pw)
- Atmospheric pressure (Patm)
- Initial pressure inside the cylinder. (P1)
2) We will formulate an equation balancing all upward and downward pressures.
P1= Patm + Pw + Pspring
3) We will calculate each of the pressures separately.
P = F/A
F= ks
k= 38×1000 =38000 N m
s= 2.5 /1000 = (2.5x10^-3) m
F = 38000×(2.5x10^-3) = 95 N
A = 30/10000 = (30x10^-4) m2
P = 95 / (30x10^-4)
Pspring ≅ 3167 Pa
P = F/A
F = W = mg
W = 2×9.81 = 19.62 N
A = 30/10000 = (30x10^-4) m2
P = 19.62 / (30x10^-4)
Pw = 654 Pa
P = 1atm = 101325 Pa
Patm = 101325 Pa
4) We will add all the downward pressures to reach the final answer (initial pressure inside the cylinder).
P1= Patm + Pw + Pspring
P1= 101325+654+3167
P1= 105146 Pa