Work energy principle and power

In summary, a girl with a mass of 50 kg travels down a water slide with an initial speed of 2 m/s and descends 5m. If there is no resistance, her final speed at the bottom would be 10.2 m/s. However, with an average resistance of 40N, her actual final speed is 8m/s. Using the work-energy principle, the length of the water slide is 25m, which differs from the textbook answer of 37.5m.
  • #1
Shah 72
MHB
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A girl of mass 50 kg travels down a water slide. She starts at the top with a speed of 2 m/s and descends through a vertical height of 5m.
a) Assuming that there is no resistance, find her speed when she reaches the bottom of the slide
I got the ans 10.2m/ s
b) the girl's actual final speed is 8m/s because there is resistance of average value of 40N. Find the length of the water slide.
I get the ans 37.5
The ans in textbook is 25m
Pls help
 
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  • #2
Shah 72 said:
A girl of mass 50 kg travels down a water slide. She starts at the top with a speed of 2 m/s and descends through a vertical height of 5m.
a) Assuming that there is no resistance, find her speed when she reaches the bottom of the slide
I got the ans 10.2m/ s
b) the girl's actual final speed is 8m/s because there is resistance of average value of 40N. Find the length of the water slide.
I get the ans 37.5
The ans in textbook is 25m
Pls help
I got the ans of 25m using work energy principle.
Thanks!
 

1. What is the work energy principle?

The work energy principle states that the work done on an object is equal to the change in its kinetic energy. This means that when a force is applied to an object, causing it to move, the work done by that force is equal to the change in the object's speed or velocity.

2. How is the work energy principle related to power?

Power is the rate at which work is done. This means that the work energy principle can also be used to calculate power. By dividing the work done by the time it takes to do that work, we can determine the power being exerted on an object.

3. Can the work energy principle be applied to all types of motion?

Yes, the work energy principle can be applied to all types of motion, including linear, rotational, and even oscillatory motion. As long as there is a force acting on an object and causing it to move, the work energy principle can be used to calculate the work done and the resulting change in kinetic energy.

4. How does the work energy principle apply to real-life situations?

The work energy principle is applicable in many real-life situations, such as lifting objects, driving a car, or throwing a ball. It helps us understand the relationship between work, energy, and motion, and allows us to calculate the amount of force and power needed to perform various tasks.

5. Is the work energy principle a universal law of physics?

Yes, the work energy principle is a fundamental law of physics that applies to all objects and systems. It is a crucial concept in understanding the behavior of physical systems and is used extensively in various fields of science and engineering.

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