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olganol [36]
3 years ago
5

An elite tour de france cyclist can maintain an output of 420 watts during a sustained climb. at this output power, how long wou

ld it take a 78 kg cyclist (including the mass of his bike) to climb the famed 1100 m high alpe d'huez mountain stage? neglect any friction.
Physics
1 answer:
julia-pushkina [17]3 years ago
7 0
<span>2002 seconds, or 33 minutes, 22 seconds. First, let's calculate how many joules it will take to lift 78 kg against gravity for 1100 meters. So: 78 kg * 9.8 m/s^2 * 1100 m = 840840 kg*m^2/s^2 Now a watt is defined as kg*m^2/s^3, so a division of the required joules should give us a convenient value of seconds. So: 840840 kg*m^2/s^2 / 420 kg*m^2/s^3 = 2002 seconds. And 2002 seconds is the same as 33 minutes, 22 seconds.</span>
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6. If a drag racer wins the final round of herrace by going an average speed of 320 m/sin 4.5 seconds, what distance did he cove
Ivan

We want to calculate the distance covered by the drag racer. Recall, the formula for calculating distance is expressed as

Distance = speed x time

From the information given,

speed = 320 m/s

time = 4.5 s

By substituting these values into the formula, we have

Distance = 320 m/s x 4.5s

s cancels out. We are left with m. Thus,

Distance = 1440m

4 0
1 year ago
a 1 m length of string is wrapped around a solid disk, of mass .25 kg and a radius of .30m, mounted on a frictionless axle. the
Nezavi [6.7K]

Answer:

60 rad/s

Explanation:

∑τ = Iα

Fr = Iα

For a solid disc, I = ½ mr².

Fr = ½ mr² α

α = 2F / (mr)

α = 2 (20 N) / (0.25 kg × 0.30 m)

α = 533.33 rad/s²

The arc length is 1 m, so the angle is:

s = rθ

1 m = 0.30 m θ

θ = 3.33 rad

Use constant acceleration equation to find ω.

ω² = ω₀² + 2αΔθ

ω² = (0 rad/s)² + 2 (533.33 rad/s²) (3.33 rad)

ω = 59.6 rad/s

Rounding to one significant figure, the angular velocity is 60 rad/s.

8 0
3 years ago
Which of the following statements are true of thermal energy and kinetic energy?
Irina-Kira [14]
This question is asking you to determine if individual atoms or systems, or both have these types of energy. A system would be "all the molecules or atoms" whereas an individual atom is "each of the molecules or atoms."

Answers: 

A. All the molecules or atoms in motion have kinetic energy.

B. Each molecule or atom in motion has kinetic energy.

D. All the molecules or atoms in motion have thermal energy.

The only incorrect answer is C because individual atoms don't have thermal energy, only when they interact with other atoms. Still, atoms do have kinetic energy, which has the potential to turn into heat energy in these interactions.

Hope this helps!
7 0
3 years ago
You pull a solid nickel ball with a density of 8.91 g/cm3 and a radius of 1.40 cm upward through a fluid at a constant speed of
Sunny_sXe [5.5K]

Answer:

P = 1.090\,N

Explanation:

The constant speed means that ball is not experimenting acceleration. This elements is modelled by using the following equation of equilibrium:

\Sigma F = P - W + F_{D}

\Sigma F = P - \rho \cdot V \cdot g + c\cdot v = 0

Now, the exerted force is:

P = \rho \cdot V \cdot g - c\cdot v

The volume of a sphere is:

V = \frac{4\cdot \pi}{3}\cdot R^{3}

V = \frac{4\cdot \pi}{3}\cdot (0.014\,m)^{3}

V = 1.149\times 10^{-5}\,m^{3}

Lastly, the force is calculated:

P = (8910\,\frac{kg}{m^{3}} )\cdot (1.149\cdot 10^{-5}\,m^{3})\cdot (9.81\,\frac{m}{s^{2}} )+(0.950\,\frac{kg}{s})\cdot (0.09\,\frac{m}{s} )

P = 1.090\,N

5 0
3 years ago
Which statement is correct? (2 points) Select one:
Olin [163]
<span>The correct answer is B - Light can travel in a vacuum, and its speed is constant if the source is moving or stationary.</span>
7 0
3 years ago
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