1.)
Velocity is in m/s, and acceleration is in m/s^2 like you said. Because of this, we can calculate this by dividing the speed by the time it took to get to that speed.
(20 meters/second) / 10 seconds = 2 meters/ second^2
2.)
Same thing with the first one.
(100 meters/second) / 4 seconds = 25 meters / seconds^2
The work done by the elephant to lift one log is the force multiplied by the height at which the log has been lifted:

And so, the total work done to lift the 7 logs is 7 times the work done to lift each log:
Velocity, unlike speed, includes a direction.
Velocity is a vector quantity which is defined by magnitude and direction.
Speed is a scalar quantity. It is the rate at which an object moves regardless of which direction.
Answer:

Explanation:
If the weight is a linear function of the amount of fuel, the following correlation is fulfilled :

we solve the equation:

Answer:
h₍₁₎ = 495,1 meters
h₍₂₎ = 480,4 m
h₍₃₎ = 455,9 m
...
..
Explanation:
The exercise is "free fall". t = 
Solving with this formula you find the time it takes for the stone to reach the ground (T) = 102,04 s
The heights (h) according to his time (t) are found according to the formula:
h(t) = 500 - 1/2 * g * t²
Remplacing "t" with the desired time.