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2 years ago

Simon can climb up the balcony (5.11 m) in 4.2 seconds. What is Simon’s power?

Physics

1 answer:

dedylja [7]2 years ago

3 0

Answer:

77.3W (to 3sf)

Explanation:

weight = mass × gravtaional field strength

= 6.35kg × 10N/kg

= 63.5N

weight = force = 63.5N

work done = force × distance

= 63.5N × 5.11m

= 324.485J

power = $\frac{work done}{elapsed time}$

= $\frac{324.485J}{4.2s}$

= 77.3W (to 3sf)

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A heat engine operating between energy reservoirs at 20?c and 600?c has 30% of the maximum possible efficiency.

Anarel [89]

<span>The maximum possible efficiency, i.e the efficiency of a Carnot engine , is give by the ratio of the absolute temperatures of hot and cold reservoir.
η_max = 1 - (T_c/T_h)

For this engine:
η_max = 1 - [ (20 +273)K/(600 + 273)K ] = 0.66 = 66%

The actual efficiency of the engine is 30%, i.e.
η = 0.3 ∙ 0.664 = 0.20 = 20 %

On the other hand thermal efficiency is defined as the ratio of work done to the amount of heat absorbed from hot reservoir:
η = W/Q_h

So the heat required from hot reservoir is:
Q_h = W/η = 1000J / 0.20 = 5000J</span>

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3 years ago

A 878-kg (1940 lb) dragster, starting from rest, attains a speed of 25.9 m/s (57.9 mph) in 0.62 s. (a) Find the average accelera

salantis [7]

Answer:

41.8m/s^2

Explanation:

Since the dragster starts from rest, initial velocity (u) = 0m/s, final velocity (v) = 25.9m/s, time (t) = 0.62s

From the equations of motion, v = u + at

a = (v - u)/t = (25.9 - 0)/0.62 = 25.9/0.62 = 41.8m/s^2

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3 years ago

A rock is being twirled in a circle on the end of a string. The string provides the centripetal force needed to keep the ball mo

KonstantinChe [14]

Answer:

Explanation:

The force of tension exerted by the string on the rock acts as centripetal force, so its direction is always towards the centre of the circle.

However, the direction of motion of the rock is always tangential to the circle: this means that the force is always perpendicular to the direction of motion of the rock.

As we know, the work done by a force on an object is

$W=Fd cos \theta$

where

F is the magnitude of the force

d is the displacement of the object

$\theta$ is the angle between the force and the displacement

In this situation, F and d are perpendicular, so $\theta=90^{\circ}$ , therefore $cos \theta = 0$ and the work done is zero:

$W=0$

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3 years ago

If an object has a mass of 10 kilograms, how much does it weigh in newtons?

schepotkina [342]

10 kilograms of mass weighs 98.1 newtons on Earth,
16.2 newtons on the Moon, 37.1 newtons on Mars,
and other weights in other places.

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3 years ago

Please help with these questions. All questions are in the image.

S_A_V [24]

1) Average speed

2) Displacement

Explanation:

Speed is a scalar quantity which gives a measure of how fast a body is moving. It is equal to the ratio between the distance travelled by an object and the time taken to cover that distance:

$speed = \frac{d}{\Delta t}$

where

d is the distance covered

$\Delta t$ is the time taken

It is important to note that being a scalar, speed does not have any direction. Moreover, distance is also a scalar quantity, which corresponds to the total length of the path covered by the object, regardless on the direction taken.

So, the equation "travelled distance/elapsed time" corresponds to the average speed. (where the term average refers to the fact we are not measuring the speed at a specific instant in time, but on a certain time interval $\Delta t$ .

Velocity is a vector quantity, so it has both a magnitude and a direction.

The magnitude of the velocity is given by:

$velocity=\frac{\Delta x}{\Delta t}$

where

$\Delta x$ is the change in position (or displacement) of the object

$\Delta t$ is the time taken

And the direction of the velocity corresponds to the direction of the displacement.

We must note that while distance does not depend on the direction, displacement does. In fact, displacement measures the difference between the initial and final position of the object.

Therefore, the equation "change in position / elapsed time" is equal to the average velocity.

Learn more about speed and velocity:

brainly.com/question/8893949 (speed)

brainly.com/question/5063905 (speed vs velocity)

brainly.com/question/5248528 (velocity)

#LearnwithBrainly

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3 years ago