# Calculating Force Needed to Lift Lid in Denver

• lalahelp
In summary, A lid is put on a box that is 14 cm long, 12 cm wide, and 8.0 cm tall and the box is then evacuated until its inner pressure is 9.0x10^4 Pa. To calculate the force required to lift the lid, the difference between the atmospheric pressure in Denver (67.5 kPa) and the pressure inside the box (90 kPa) is multiplied by the surface area of the lid (14 cm x 12 cm). This results in a force of -378 N, indicating that the lid would be pushed down rather than lifted. This could be due to the fact that the pressure outside is now lower than the pressure inside the box.

## Homework Statement

A lid is put on a box that is 14 cm long, 12 cm wide, and 8.0 cm tall and the box is then evacuated until its inner pressure is 9.0 104 Pa.

How much force is required to lift the lid in Denver on a day when the atmospheric pressure is 67.5 kPa (2/3 the value at sea level)?

## The Attempt at a Solution

(67500-90000)*.o168
=-378 N

lalahelp said:

## Homework Statement

A lid is put on a box that is 14 cm long, 12 cm wide, and 8.0 cm tall and the box is then evacuated until its inner pressure is 9.0 104 Pa.
Can you clarify that pressure value?

the pressure value is 90000 pa

lalahelp said:
the pressure value is 67500 pa

9.0 104 Pa is 67500 pa ?

Is it supposed to be 9.0x104 Pa ?

Yeh I messed up my bad sorry

Okay, then your working seems fine. What does it mean if the pressure outside is now less than what the pressure in the box is (or was!).

## What is the formula for calculating the force needed to lift a lid in Denver?

The formula for calculating the force needed to lift a lid in Denver is F = m * a, where F is the force in Newtons, m is the mass of the lid in kilograms, and a is the acceleration due to gravity in Denver (9.81 m/s^2).

## How does the altitude of Denver affect the force needed to lift a lid?

The higher altitude of Denver means that the acceleration due to gravity is slightly less (9.81 m/s^2 compared to 9.8 m/s^2 at sea level). This means that the force needed to lift a lid in Denver will be slightly less than at sea level.

## What other factors besides altitude can affect the force needed to lift a lid?

Other factors that can affect the force needed to lift a lid include the weight and size of the lid, the material it is made of, and the angle at which it is being lifted. Friction between the lid and the surface it is resting on can also affect the force needed.

## Is there a specific unit of measurement for force needed to lift a lid?

Yes, the unit of measurement for force is Newtons (N). However, other units such as pounds (lb) or kilograms (kg) may also be used depending on the context and preference.

## Can the formula for calculating the force needed to lift a lid be applied to other objects?

Yes, the formula F = m * a can be applied to any object, not just lids. It is a general formula for calculating force based on mass and acceleration, which can be used in a variety of situations in physics and engineering.