A skateboarder with a mass of 67.0 kilograms (including the skateboard) rolls down from the top of a ramp, reaching a velocity o
f 7.30 meters per second at the bottom of the ramp. Assuming friction is 0, what was the potential energy of the skateboarder at the top of the ramp?
1,785 J.
59.70 J.
74.30 J.
489.1 J.
1,785 J.
59.70 J.
74.30 J.
489.1 J.
1 answer:
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Answer:
The total distance is 130.2 [m]
Explanation:
In order to solve this problem we must use the expressions of kinematics. The clue to solve this problem is that the cart starts from rest, i.e. its initial speed is zero.
where:
Vf = final velocity [m/s]
Vo = initial velocity = 0
a = acceleration = 3 [m/s²]
t = time = 8[s]
Vf = 0 + (3*8)
Vf = 24 [m/s]
With this velocity we can calculate the displacement using the following expression.
where
x = distance traveled [m]
24² = 0 + (2*3*x)
x = 576/(6)
x = 96 [m]
Note: The positive sign in the equations is because the car is accelerating, it means its velocity is increasing.
The other important clue to solve this problem in the second part is that the final velocity is now the initial velocity.
We must calculate the final velocity.
Vf = final velocity [m/s]
Vi = initial velocity = 24 [m/s]
a = desacceleration = 1.6 [m/s²]
t = time = 15 [s]
Vf = 24 - (1.6*15)
Vf = 21.6 [m/s]
With this velocity, we can calculate the displacement using the following expression.
where
x = distance traveled [m]
21.6² = 24² - (2*1.6*x)
x = 109.44/(3.2)
x = 34.2 [m]
Note: The negative sign in the equations is because the car is desaccelerating, it means its velocity is decreasing.
Therefore the total distance is Xt = 34.2 + 96 = 130.2 [m].
Answer:
Explanation:
Since <em>light is so fast</em> we can assume no time passes between the lightning strikes and we observe it. We want to know then how far away did the strike occur for the sound to take 16s to reach our ears. Since the definition of velocity tells us that , we can write