From t=10.0 seconds to t=15.0 seconds, a space shuttle increased speed from 57 m/s to 99 m/s. What was the average acceleration
1 answer:
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Answer:
a) It is moving at when reaches the ground.
b) It is moving at when reaches the ground.
Explanation:
Work energy theorem states that the total work on a body is equal its change in kinetic energy, this is:
(1)
with W the total work, Ki the initial kinetic energy and Kf the final kinetic energy. Kinetic energy is defined as:
(2)
with m the mass and v the velocity.
Using (2) on (1):
(3)
In both cases the total work while the objects are in the air is the work gravity field does on them. Work is force times the displacement, so in our case is weight (w=mg) of the object times displacement (d):
(4)
Using (4) on (3):
(5)
That's the equation we're going to use on a) and b).
a) Because the branch started form rest initial velocity (vi) is equal zero, using this and solving (5) for final velocity:
b) In this case the final velocity of the boulder is instantly zero when it reaches its maximum height, another important thing to note is that in this case work is negative because weight is opposing boulder movement, so we should use -mgd:
Solving for initial velocity (when the boulder left the volcano):
The acceleration of the bike is equal to opposing the movement (to the right).
Why?
Since after the rider slams the brakes, the bike came to a stop, we know that the acceleration is opposite to the velocity/movement.
We can use the following equation to calculate the acceleration:
So, substituting, we have: (let's consider negative to the left and positive to the right)
The negative sign means that the acceleration's direction is opposite to the movement.
Hence, we have that the acceleration is equal to opposing the movement (to the right).
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