Why Does the Scale Show 76 kg in the Elevator?

AI Thread Summary
The scale reading of 76 kg in the elevator indicates that the elevator is accelerating upwards, resulting in an apparent increase in weight. To analyze the situation, the force corresponding to the 76 kg can be calculated by multiplying it by the acceleration due to gravity (g). This force represents the net force acting on the person in the elevator. Understanding this relationship helps in correlating the actual mass of 65 kg with the observed weight on the scale. The discussion emphasizes the importance of recognizing how acceleration affects perceived weight in an accelerating frame.
drewdiddy
Messages
13
Reaction score
0

Homework Statement



Normal mass is 65kg. I get into an elevator, on a scale in the elevator and it reads 76 kg. Find a along with direction.

Homework Equations



w = mg + ma

The Attempt at a Solution



Obviously the elevator is accelerating upwards due to the apparent increase in mass. However, for the life of me I am having issues setting up this basic problem. I don't need any answers, just a shove in the right direction. How do I correlate the actual mass with the 76 kg? Thank you.
 
Physics news on Phys.org
Hi drewdiddy,

What force (acting on you) does the reading of 76kg represent?

In other words, you can find a force from the 76kg reading by multiplying it by g, and that force is acting on you. What force is it?
 
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

Calculate elevator acceleration using mass
Replies
9
Views
4K
Mechanics: Elevator Accelerating Downward
Replies
10
Views
4K
Solving for weight and mass in kg in an elevator
Replies
2
Views
3K
Forces and Elevators: Free-Body Diagrams and Calculations
Replies
9
Views
6K
Understanding Sign Conventions in Elevator Tension Problems
Replies
6
Views
3K
Action-Reaction Forces on an Elevator
Replies
5
Views
3K
Forces, elevator, acceleration -- I have the answer, just explain it....
Replies
2
Views
12K
The elevator, the scale, and the wrong answer: Solving the Puzzle
Replies
7
Views
9K
Apparent weight of a man standing in an elevator
Replies
24
Views
7K
Scale Reading in Elevator: Mass, Acceleration, and Velocity Calculations
Replies
6
Views
3K

Hot Threads

Recent Insights

Back
Top