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Why are the alkali metals likely to react with group 17 elements?
1 answer:
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Answer:
In an ideal pulley system is assumed as a perfect system, and the efficiency of the pulley system is taken as 100% such that there are no losses of the energy input to the system through the system's component
However, in a real pulley system, there are several means through which energy is lost from the system through friction, which is converted into heat, sound, as well as other forms of energy
Given that the mechanical advantage = Force output/(Force input), and that the input force is known, the energy loss comes from the output force which is then reduced, and therefore, the Actual Mechanical Advantage (AMA) is less than the Ideal Mechanical Advantage of an "ideal" pulley system
The relationship between the actual and ideal mechanical advantage is given by the efficiency of the pulley system as follows;
Explanation:
(a) 29.8 m/s
To solve this problem, we start by analyze the vertical motion first. This is a free fall motion, so we can use the following suvat equation:
where, taking upward as positive direction:
is the final vertical velocity
is the initial vertical velocity (zero because the pebble is launched horizontally)
is the acceleration of gravity
s = -25.0 m is the displacement
Solving for vy,
(downward, so we take the negative solution)
The pebble also have a horizontal component of the velocity, which remains constant during the whole motion, so it is
So, the final speed of the pebble as it strikes the ground is
(b) 29.8 m/s
In this case, the pebble is launched straight up, so its initial vertical velocity is
So we can find the final vertical velocity using the same suvat equation as before:
(downward, so we take the negative solution)
The horizontal speed instead is zero, since the pebble is initially launched vertically, so the final speed is just equal to the magnitude of the vertical velocity:
v = 29.8 m/s
(c) 29.8 m/s
This case is similarly to the previous one: the only difference here is that the pebble is launched straight down instead than up, therefore
Using again the same suvat equation:
(downward, so we take the negative solution)
As before, the horizontal speed instead is zero, since the pebble is initially launched vertically, so the final speed is just equal to the magnitude of the vertical velocity:
v = 29.8 m/s
We notice that the final value of the speed is always the same in all the three parts, so it does not depend on the direction of launching. This is due to the law of conservation of energy: in fact, the initial mechanical energy of the pebble (kinetic+potential) is the same in all three cases (because the height h does not change, and the speed v does not change either), and the kinetic energy gained during the fall is also the same (since the pebble falls the same distance in all 3 cases), therefore the final speed must also be the same.