Lower resistivity means higher conductivity: among these materials, the best conductor is silver, therefore it must be the material with lowest resistivity among those. We can also have a look at the value of resistivity of the different materials listed in the problem, to check our answer. The resistivities of the materials are the following:
Wood:

Salt water:

Silver:

Lead:

<span>We see that the material with lowest resistivity among those is silver, therefore the correct answer is silver.</span>
Answer:
∆h = 0.071 m
Explanation:
I rename angle (θ) = angle(α)
First we are going to write two important equations to solve this problem :
Vy(t) and y(t)
We start by decomposing the speed in the direction ''y''


Vy in this problem will follow this equation =

where g is the gravity acceleration

This is equation (1)
For Y(t) :

We suppose yi = 0

This is equation (2)
We need the time in which Vy = 0 m/s so we use (1)

So in t = 0.675 s → Vy = 0. Now we calculate the y in which this happen using (2)

2.236 m is the maximum height from the shell (in which Vy=0 m/s)
Let's calculate now the height for t = 0.555 s

The height asked is
∆h = 2.236 m - 2.165 m = 0.071 m
Answer:
17.565 kgm/s
Explanation:
Momentum = mass × velocity
I = mv..................... Equation 1
But we can calculate the value of v using the equation of motion under gravity.
v² = u²+2gs............. Equation 2
Where u = initial velocity, s = maximum heigth, g = acceleration due to gravity.
Given: u = 0 m/s (at the maximum heigth), s = 7.0 m.
Constant: g = 9.8 m/s²
Substitute these values into equation 2
v² = 0²+ 2×7×9.8
v² = 137.2
v = √137.2
v = 11.71 m/s.
Also given: m = 1.50 kg
substitute these values into equation 1
Therefore,
I = 1.5×11.71
I = 17.565 kgm/s
This correct answer would be C