Magnitude of force (elevator question)

In summary, Pat Summit (60 kg) is in an elevator with a velocity of 10.0 m/s downward and an acceleration of 5.00 m/s^2 upward. Using the equation F=ma, the magnitude of the force exerted by the floor of the elevator on her can be calculated. However, there seems to be some confusion regarding the equation used to find the answer.
  • #1
studybug
2
0

Homework Statement


Pat Summit (60 kg) is standing in an elevator which has a
velocity of 10.0 m/s downward and an acceleration of 5.00
m/s^2 upward. What is the magnitude of the force exerted by
the floor of the elevator on her? Is the elevator speeding up
or slowing down?

Homework Equations


F=ma..

The Attempt at a Solution


I really am not sure where to start here..
I drew a free body diagram but, does acceleration count as a force?
How does velocity come into play?
 
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  • #2
On the free body diagram, there is normal reaction and weight. So what is the resultant force 'ma' equal to?
 
  • #3
I got the answer :)
using V*m + W - F = m*a_y... so..
F = (60*9.81) - (-5m/s^2)*m + (60kg * 10m/s)
thanks for the help.
 
  • #4
studybug said:
I got the answer :)
using V*m + W - F = m*a_y... so..
F = (60*9.81) - (-5m/s^2)*m + (60kg * 10m/s)
thanks for the help.

While I am glad to see that you got your answer, your equation doesn't seem to 'add' up

as

60*9.81 = N

5 m/s2 * 60kg = N

60kg*10m/s = kgm/s


which means you are adding force+force+ momentum and getting force. :confused:
 

1. What is the magnitude of force in an elevator?

The magnitude of force in an elevator is typically equal to the weight of the elevator and its contents. This is due to the fact that the elevator experiences a force from the Earth's gravitational pull, known as the weight force.

2. How does the magnitude of force change in an elevator?

The magnitude of force in an elevator can change depending on the direction of motion. When the elevator is moving upwards or downwards at a constant speed, the magnitude of force remains the same. However, when the elevator is accelerating or decelerating, the magnitude of force will change due to the changing velocity.

3. Does the mass of the elevator affect the magnitude of force?

Yes, the mass of the elevator does affect the magnitude of force. The greater the mass of the elevator, the greater the weight force it experiences, resulting in a greater magnitude of force.

4. What is the relationship between the magnitude of force and the speed of the elevator?

The magnitude of force and the speed of the elevator are indirectly proportional. This means that as the speed of the elevator increases, the magnitude of force decreases, and vice versa. This is due to the fact that a higher speed requires a greater amount of force to maintain the motion.

5. How does the direction of motion affect the magnitude of force in an elevator?

The direction of motion does not typically affect the magnitude of force in an elevator. As long as the elevator is moving at a constant speed, the magnitude of force will remain the same regardless of the direction of motion.

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