A stone is dropped from rest from the top of a cliff into a pond below. If its initial height is 10 m, what is its speed when it
1 answer:
Answer:
14 m/s
Explanation:
The motion of the stone is a free fall motion, so an accelerated motion with constant acceleration g = 9.8 m/s^2 towards the ground. So, we can use the following SUVAT equation:
where
v is the final speed of the stone as it reaches the water
u = 0 is the initial speed
g = 9.8 m/s^2 is the acceleration
h = 10 m is the distance covered by the stone
Solving for v, we find
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Let's start with energy conservation law:
This equation tells us that kinetic energy of two carts before the collision and 3 quarters of explosion energy is beign transfered to kinetic energy of the cart after the collision.
Let's write down momentum conservation law:
Because both carts have the same mass we can cancel those out:
Now we have our system of equation that we have to solve:
Part A
We need to solve our system for
. We will solve second equation for 
and then plug that in the first equation.
Now we have to plug this in the first equation:
We will multiply the first equation with 2 and divide by m:
Now we plug in the second equation into first one:
We end up with quadratic equation that we have to solve, I won't solve it by hand.
Coefficients are:
Solutions are:
Part B
We do the same thing here, but we must express from momentum equation:
Now we plug this into our energy conservation equation:
Again we end up with quadratic equation. Coefficients are:
Solutions are:
Let's start with energy conservation law:
This equation tells us that kinetic energy of two carts before the collision and 3 quarters of explosion energy is beign transfered to kinetic energy of the cart after the collision.
Let's write down momentum conservation law:
Because both carts have the same mass we can cancel those out:
Now we have our system of equation that we have to solve:
Part A
We need to solve our system for
Now we have to plug this in the first equation:
We will multiply the first equation with 2 and divide by m:
Now we plug in the second equation into first one:
We end up with quadratic equation that we have to solve, I won't solve it by hand.
Coefficients are:
Solutions are:
Part B
We do the same thing here, but we must express
Now we plug this into our energy conservation equation:
Again we end up with quadratic equation. Coefficients are:
Solutions are: