How much gravitational potential energy does a 45.2 kg object have when it is 21.9m above the ground?
1 answer:
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Hi there!
A.
Since the can was launched from ground level, we know that its trajectory forms a symmetrical, parabolic shape. In other words, the time taken for the can to reach the top is the same as the time it takes to fall down.
Thus, the time to its highest point:
Now, we can determine the velocity at which the can was launched at using the following equation:
In this instance, we are going to look at the VERTICAL component of the velocity, since at the top of the trajectory, the vertical velocity = 0 m/s.
Therefore:
***vsinθ is the vertical component of the velocity.
Solve for 'v':
Now, recall that:
Plug in the expression for velocity:
B.
We can use the same process as above, where T' = 2T and Th = T.
C.
The work done in part B is 4 times greater than the work done in part A.
Answer:
Kf = 470 mJ
Explanation:
- According the work-energy theorem, the change in the kinetic energy of one object, is equal to the net work done on it.
- Since the puck is initially at rest, the change is kinetic energy is just the final kinetic energy of the puck.
- Assuming that the net force is horizontal, and causes a horizontal displacement also, we can find the net work on the puck as follows:
- As we have already said, (1) is equal to the final kinetic energy of the puck:
- ⇒ Kf = 470 mJ (2)