Answer:
2%
Explanation:
75% of the mass contains hydrogen 25% helium and all other elements comprising only of 2%
I don’t know but I am pretty sure b
B) 48.0 m/s
We can actually start to solve the problem from B for simplicity.
The motion of the rock is a uniformly accelerated motion (free fall), so we can find the final speed using the following suvat equation

where
is the final velocity
is the initial velocity (positive since we take downward as positive direction)
is the acceleration of gravity
s = 110 m is the vertical displacement
Solving for v, we find the final velocity (and so, the speed of the rock at impact):

A) 3.67 s
Now we can find the time of flight of the rock by using the following suvat equation

where
is the final velocity at the moment of impact
is the initial velocity
is the acceleration of gravity
t is the time it takes for the rock to reach the ground
And solving for t, we find

Answer:
a = 6.4 [m/s²]
Explanation:
To solve this problem we must use Newton's second law, which tells us that the sum of forces on a body is equal to the product of mass by acceleration. In this way, we have the following equation.
∑F = m*a
where:
∑F = sum of forces (horizontal force = 40 [N] and friction force = 8 [N])
m = mass of the block = 5 [kg]
a = acceleration [m/s²]
Now replacing:
![40-8=5*a\\32 = 5*a\\a=6.4[m/s^{2} ]](https://tex.z-dn.net/?f=40-8%3D5%2Aa%5C%5C32%20%3D%205%2Aa%5C%5Ca%3D6.4%5Bm%2Fs%5E%7B2%7D%20%5D)
Note: the sign of the friction force is negative since this force is acting against the movement of the block.