How do I find the work and power if I have a mass in Newtons?

AI Thread Summary
To find work when climbing stairs, it's essential to convert weight correctly into Newtons without unnecessary multiplications. The user initially converted their weight of 135 pounds to Newtons using a factor of 4.5, resulting in 607 Newtons. However, multiplying by 9.8 m/s² again was incorrect, as the force is already expressed in Newtons. Work is calculated as force multiplied by distance, so only the force in Newtons and the distance in meters should be used. Clarifying units and avoiding redundant calculations is crucial for accurate results.
MoreZitiPlease
Messages
107
Reaction score
0
Im trying to find my work when climbing up stairs. If I convert my weight into Newtons, do I still need to multiply it by 9.8? Since i weigh 135, I multiplied that by 4.5 to get my weight in Newtons. I then multiplied that by 9.8, after that I multiplied that by 3.0 m ( the distance of the stairs). I got a really big number

that okay?
 
Physics news on Phys.org
Why did you multiply by 4.5? 135 what?
 
135 pounds

1pound=4.45 Newtons
 
So then why did you multiply by 9.8 again if you already have your weight in Newtons?
 
No, it's not ok. You only put units on the height of the stairs. Put units on EVERYTHING. You weight 135? 135 what? I'm guessing lbs. Don't make me guess. So then 135lb*4.5N/lb=607N is already a force unit (Newtons=kg*m/sec^2). I'm guessing when you said 9.8 you mean 9.8m/sec^2. Work is force times distance. Is 607N*9.8m/sec^2 even a force unit? Can you answer your own question? "If I convert my weight into Newtons, do I still need to multiply it by 9.8?". Yes or no?
 
no, you dont..

okay, thanks

let me change my data

thanks
 

Thread 'Struggling to understand the concept of this question (ice cube in water optics question)'

TL;DR Summary: I came across this question from a Sri Lankan A-level textbook. Question - An ice cube with a length of 10 cm is immersed in water at 0 °C. An observer observes the ice cube from the water, and it seems to be 7.75 cm long. If the refractive index of water is 4/3, find the height of the ice cube immersed in the water. I could not understand how the apparent height of the ice cube in the water depends on the height of the ice cube immersed in the water. Does anyone have an...
View full post »
Thread 'Variable mass system : water sprayed into a moving container'

Thread 'Variable mass system : water sprayed into a moving container'

Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...
View full post »

Similar threads

Work, energy, power tennis ball problem
Replies
2
Views
2K
Having a hard time learning Newton's 2nd law
Replies
5
Views
2K
Determine the mass of the planet using Newton’s Law of Universal Gravitation
Replies
2
Views
3K
Calculating the Work Required to Climb Stairs
Replies
14
Views
8K
Relationship between material mass and weight
Replies
5
Views
2K
Finding work of a man running up stairs
Replies
6
Views
5K
Solving for Masses in an Atwood Machine
Replies
8
Views
2K
Fundamental Forces Problem: Acceleration from Planet
Replies
9
Views
1K
Negative vs Positive work on an escalator
Replies
8
Views
4K
Given time, distance and weight, how do I calculate work?
Replies
9
Views
23K

Hot Threads

Recent Insights

Back
Top