Finding accleration and tension as an elevator moves upwards/downwards.

In summary: Yes, that looks correct. Just be sure to include the units for the tension, which is in N (Newtons). So the final answers for C and D would be 9240 N and 6134 N, respectively. Great job!
  • #1
Crusaderking1
159
0

Homework Statement

A 593 N physics student stands on a bathroom scale in an 875 kg (including the student) elevator that is supported by a cable. As the elevator starts moving, the scale reads 424 N.

A. Find the magnitude of the acceleration of the elevator.

B. What is the acceleration if the scale reads 639 N?

C. What is the tension in the cable in part A?

D. What is the tension in the cable in part B?

Homework Equations



ƩF = ma

T= ma +mg

The Attempt at a Solution



A. 424-593 =60.5a
-2.79 = a

B. 639-593= 60.5a
0.76 = a

C. (875)(2.79)+(593) =T
3034 N = T

D. (875)(.76) + 593
1259 N = T

Is this right? Thanks.

Also, would acceleration stay negative for part C?
 
Physics news on Phys.org
  • #2
Lets deal with this question first.
"Also, would acceleration stay negative for part C?"

Well what did you calculate as the acceleration in part a)?
Why would you think that answer would change?

and then parts c) and D)
Which way is the elevator accelerating in part A) and Part B) ie up or down.

If the elevator is accelerating up or down, in which case then would the tension in the cable be greater or lessor than before the elevator started moving?

Draw a FBD to obtain all the forces on the elevator.

And what does this mean in the problem
" 875 kg (including the student) elevator "
 
  • #3
256bits said:
Lets deal with this question first.
"Also, would acceleration stay negative for part C?"

Well what did you calculate as the acceleration in part a)?
Why would you think that answer would change?

and then parts c) and D)
Which way is the elevator accelerating in part A) and Part B) ie up or down.

If the elevator is accelerating up or down, in which case then would the tension in the cable be greater or lessor than before the elevator started moving?

Draw a FBD to obtain all the forces on the elevator.

And what does this mean in the problem
" 875 kg (including the student) elevator "

You're right, part A is negative so I'm guessing I use that same value for part C.

The elevator is accelerating down in part A and up in part B.

Tension would be greater as it accelerates upward.

I will try to re-solve for C and D and answer back, but I think part A and B are right. Thanks.
 
Last edited:
  • #4
ok

I think upwards, T-mg=ma
So, T-8575=665
T= 9240 N

I think downwards, T-mg=-ma
So, T-8575=-2441.25
T= 6134 N

Upwards a=0.760
Downwards a=2.79

Sound better?
 
  • #5


Yes, your solutions for parts A-D seem to be correct. And yes, acceleration would stay negative for part C because the elevator is still moving downwards.
 

1. How do you calculate acceleration in an elevator?

To calculate the acceleration in an elevator, you need to determine the change in velocity over time. This can be done by dividing the change in velocity by the time it took for the change to occur. The formula for acceleration is: a = (vf - vi) / t, where a is acceleration, vf is the final velocity, vi is the initial velocity, and t is the time.

2. What factors affect the acceleration of an elevator?

The acceleration of an elevator can be affected by several factors, including the weight of the elevator and its occupants, the force of the motor, and the friction between the elevator and the elevator shaft. The design of the elevator and the speed at which it is moving can also impact the acceleration.

3. How does the tension in the elevator cables change as the elevator moves?

As the elevator moves, the tension in the elevator cables will change. When the elevator is moving upwards, the tension in the cables will increase as the weight of the elevator and its occupants is pulled upwards. When the elevator is moving downwards, the tension in the cables will decrease as the weight of the elevator and its occupants is pushing down on the cables.

4. Can the acceleration and tension in an elevator be different for upward and downward movements?

Yes, the acceleration and tension in an elevator can be different for upward and downward movements. This is because different forces are acting on the elevator depending on the direction it is moving. For example, when moving upwards, the elevator experiences a greater gravitational force, which can impact the acceleration and tension.

5. How can the acceleration and tension in an elevator be measured?

The acceleration and tension in an elevator can be measured using various instruments such as accelerometers, strain gauges, and load cells. These instruments can provide precise measurements of the forces acting on the elevator and help calculate the acceleration and tension. Engineers and technicians also use mathematical equations and computer simulations to analyze and measure these factors in elevators.

Similar threads

  • Introductory Physics Homework Help
Replies
10
Views
2K
  • Introductory Physics Homework Help
Replies
19
Views
701
  • Introductory Physics Homework Help
Replies
6
Views
2K
  • Introductory Physics Homework Help
Replies
4
Views
746
  • Introductory Physics Homework Help
Replies
3
Views
2K
  • Introductory Physics Homework Help
Replies
33
Views
6K
  • Introductory Physics Homework Help
Replies
6
Views
2K
  • Introductory Physics Homework Help
Replies
5
Views
2K
  • Introductory Physics Homework Help
2
Replies
36
Views
3K
  • Introductory Physics Homework Help
Replies
2
Views
1K
Back
Top