# Math Help - Mechanical Formulas

1. ## Mechanical Formulas

I'm not sure about these questions i'v been given. Do you know any basic formula's to use for these questions?

A strong meter rule is used as a lever and the fulcrum is placed under the mark around 90 cm. I need to find what mass would need to be placed on the long end of the lever to lift a 1kg mass on the short end?

An incline plane is used to lift a 100 kg barrel onto a drinks bar at a height of 1m. The plane is 5m long. How much force is required to roll the barrel up the plane?

2. Originally Posted by Illuminati

An incline plane is used to lift a 100 kg barrel onto a drinks bar at a height of 1m. The plane is 5m long. How much force is required to roll the barrel up the plane?
Work done is equal to the change in energy (ignoring frictional losses).

Change in energy (in Joules) is mass times height change (in metres) for a barrel (assume its at rest before and after), work done is the force (in Newtons), times the distance it moves (in metres), so:

$5 \times f=100 \times 1$

RonL

3. Originally Posted by Illuminati
A strong meter rule is used as a lever and the fulcrum is placed under the mark around 90 cm. I need to find what mass would need to be placed on the long end of the lever to lift a 1kg mass on the short end?
The moments of the two masses about the fulcrum will be equal, so:

$m \times 90=1 \times 10$

$m$ in kg

RonL

4. Originally Posted by Illuminati

I'm not sure about these questions i'v been given. Do you know any basic formula's to use for these questions?

A strong meter rule is used as a lever and the fulcrum is placed under the mark around 90 cm. I need to find what mass would need to be placed on the long end of the lever to lift a 1kg mass on the short end?

An incline plane is used to lift a 100 kg barrel onto a drinks bar at a height of 1m. The plane is 5m long. How much force is required to roll the barrel up the plane?
If you are looking for a set formula to use for these then you are up the creek. Otherwise they are all static torque problems and can be done by using
$\sum \tau = 0$

-Dan