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A bicyclist is traveling at a speed of 20.0 m/s as he approaches the bottom of a hill. He decides to coast up the hill and stops upon reaching the top. Determine the vertical height of the hill. Ignore friction and air resistance.A) 28.5 m B) 3.70 m C) 11.2 m D) 40.8 m E) 20.4 m

User Lojals
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2 Answers

3 votes

Final answer:

To determine the vertical height of the hill, we can use the principle of conservation of mechanical energy. The initial kinetic energy at the bottom of the hill is equal to the final potential energy at the top of the hill. By setting the initial kinetic energy equal to the final potential energy, we can solve for the height of the hill.

Step-by-step explanation:

To determine the vertical height of the hill, we can use the principle of conservation of mechanical energy. At the bottom of the hill, the bicyclist has only kinetic energy. At the top of the hill, the bicyclist has only potential energy. Therefore, the initial kinetic energy at the bottom of the hill is equal to the final potential energy at the top of the hill.

The formula for kinetic energy is given by K = 1/2 mv^2, where m is the mass and v is the velocity. The formula for potential energy is given by P = mgh, where m is the mass, g is the acceleration due to gravity (9.8 m/s^2), and h is the height.

The kinetic energy at the bottom of the hill is given by K = 1/2 mv^2 = 1/2 * 1 kg * 20.0 m/s * 20.0 m/s = 200 J.

The potential energy at the top of the hill is given by P = mgh, where h is the height we need to find. Since the bicyclist comes to a stop at the top of the hill, the final velocity v is 0 m/s. Therefore, the equation becomes P = mgh = 1 kg * 9.8 m/s^2 * h = 9.8h J.

Since the initial kinetic energy is equal to the final potential energy, we can set 200 J = 9.8h J and solve for h:

200 J = 9.8h J

h = 200 J / 9.8 J = 20.4 m.

Therefore, the vertical height of the hill is 20.4 m.

3 votes

Answer:

Vertical height of the hill, h = 20.4 meters

Step-by-step explanation:

Given that,

Speed of the bicyclist, v = 20 m/s

To find,

The vertical height of the hill.

Solution,

Let h is the height of the hill. When he approaches the bottom of the hill, the loss in kinetic energy is equal to the gain in potential energy. Using the conservation of energy as,


(1)/(2)mv^2=mgh


h=(v^2)/(2g)


h=((20)^2)/(2* 9.8)

h = 20.4 meters

Therefore, the vertical height of the hill is 20.4 meters. Hence, this is the required solution.

User HoaPhan
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