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3 years ago

A weightlifter expends 294 w of power lifting a weight to a height of 2 m in 10 seconds. what mass has he lifted?

1 answer:

3 0

The power of the weightlifter is equal to the ratio between the work done by it and the time taken:
$P= \frac{W}{t}$
since we know the power and the time, we can find the work done:
$W=Pt=(294 W)(10 s)=2940 J$

For the work-energy theorem, this work done by the lifter is equal to the gravitational potential energy gained by the mass, which is given by:
$U=mg \Delta h$
where m is the mass and $\Delta h$ is the increase in height. Rearranging the formula and using W=U, we can find the mass:
$m= \frac{U}{g\Delta h}= \frac{2940 J}{(9.81 m/s^2)(2 m)}=149.8 kg$

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If all of the forces acting on an object are balanced, then:

kondaur [170]

A. the direction the object is moving in will not change.

B. the acceleration of the object will be 0 m/s2

Explanation:

We can answer this problem by using Newton's second law of motion:

$\sum F = ma$

where

$\sum F$ is the net force acting on an object

m is the mass of the object

a is its acceleration

In this problem, all the forces acting on the object are balanced, therefore the net force is zero:

$\sum F=0$

which means that also the acceleration is zero:

$a=0$

Acceleration is equal to the rate of change of velocity: therefore, zero acceleration means that the velocity of the object does not change. We can now analyze the given statements:

A. the direction the object is moving in will not change. --> TRUE, because the velocity is not changing.

B. the acceleration of the object will be 0 m/s2 --> TRUE, as we stated above

c. the object will not be in motion. --> FALSE: we just know that its velocity is constant, but it can be different from zero

D. the velocity of the object will be 0 m/s. --> FALSE, for the same reason stated in C

Learn more about Newton's second law of motion:

brainly.com/question/3820012

#LearnwithBrainly

3 0

3 years ago

Which law describes how the Earth applies a gravitational force on the Moon, the Moon applies a gravitational force on Earth? *

nikdorinn [45]

The answer is Newton's 3rd Law. The reason why is because a force is a push or a pull that acts upon an object as a results of its interaction with another object. ... These two forces are called action and reaction forces and are the subject ofNewton's third law of motion. Formally stated, Newton's third law is: For every action, there is an equal and opposite reaction.

3 0

3 years ago

Read 2 more answers

Rony fills a bucket with water and whirls it in a vertical circle to demonstrate that the water will not spill from the bucket a

Romashka-Z-Leto [24]

Answer:

0 N, 3.49 m/s

Explanation:

Draw a free body diagram for the bucket at the top of the swing. There are two forces acting on the bucket: weight and tension, both downwards.

If we take the sum of the forces in the radial direction, where towards the center is positive:

∑F = ma

W + T = m v² / r

The higher the velocity that Rony swings the bucket, the more tension there will be. The slowest he can swing it is when the tension is 0.

W = m v² / r

mg = m v² / r

g = v² / r

v = √(gr)

Given that r = 1.24 m:

v = √(9.8 m/s² × 1.24 m)

v = 3.49 m/s

8 0

3 years ago

We humans are on track to increase the amount of CO2 in the atmosphere so that the concentration in the future more than double

Lapatulllka [165]

Answer:

Rapid increase in the temperature of the earth.

Explanation:

CO2 is known as a greenhouse gas. It is able to trap and retain infrared radiation in the earths atmosphere thereby causing a gradual rise in the temperature of the earth. If this doubled concentration of CO2 is sustained over a long period of time, it will eventually lead to melting of polar ice caps and consequent flooding. Gradually, the earth would be destroyed due to the scorching heat and attendant flood.

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3 years ago

How does temperature,barometric pressure,humidity,wind speed and direction, and precipitation determine the weather in a particu

Deffense [45]

Temperature is how hot or cold something is,barometric is air pressure(when the pressures high,the weather is dry)humidity is how moist the air is and how many water particles are there, wind speed and direction is how the hot and cold air is moving and how fast,which makes wind (high to low, hot to cold) precipitation is how much it is raining at that point.

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3 years ago