SIMPLE MACHINES

¿Sabías que el balancín que se encuentra en muchos parques es un ejemplo de palanca? Cuando dos niños se sientan en los dos extremos, uno quedará más arriba que otro si el balancín no está en equilibrio. Si los dos niños tienen distinta masa (que es lo normal), el balancín estará en posición de equilibrio (paralelo al suelo) si los dos se sientan a distinta distancia del centro. Se dice que el momento total de las fuerzas aplicadas debe ser cero. Con este simulador virtual puedes jugar con este balancín y familiarizarte con este concepto.

levers

A lever can be set up with unequal weights placed at different distances from the balancing point (also called the fulcrum) .

In order for the above lever to be balanced, the following equation must be satisfied.

F1 · r1 = F2 · r2

¿Sabías que el balancín que se encuentra en muchos parques es un ejemplo de palanca? Cuando dos niños se sientan en los dos extremos, uno quedará más arriba que otro si el balancín no está en equilibrio. Si los dos niños tienen distinta masa (que es lo normal), el balancín estará en posición de equilibrio (paralelo al suelo) si los dos se sientan a distinta distancia del centro. Se dice que el momento total de las fuerzas aplicadas debe ser cero. Con este simulador virtual puedes jugar con este balancín y familiarizarte con este concepto.

inclined plane or ramp

An inclined plane, also known as a ramp, is a flat tilted surface; that means it has one end higher than the other.

It is used as an aid for raising or lowering a load.The ramp makes it easier to lift something heavy, like a rock. Instead of lifting the rock straight up, you can push it a greater distance, but with less force.

If you make the ramp steeper, you'll have a shorter distance, but it will be harder to push the rock (you'll need more force).

If you make the ramp less steep, it will have to be longer, but it will be easier to push the rock.

If the block moves along the inclined plane at a constant speed, the force applied and the weight of the block are related to each other according to the formula: F · d = W · h

Exercises on levers

Paco wants to move a 25 kg rock with a 2 m crowbar. If he puts the fulcrum 20 cm from the rock. What should be the magnitude of the force applied by Paco?

Pedro weighs 250 N and Margarita weighs 300 N. They are both seated on a seesaw. If Pedro is seated 3 metres away from Margarita, how far should each be from the fulcrum of the seesaw?

Beatriz and her sister are seated on a seesaw. Carmen is 50 cm away from the fulcrum. Her sister is 25 kg and is 60 cm away from the fulcrum. How does Carmen weigh?

Lorena weighs 200 N and sits 1,5 m away from the fulcrum of a seesaw. If her friend Olga weighs 250 N and sits on the other side, how far from the fulcrum must she sit to have the seesaw balance?

Exercises on inclined planes

Maria’s mother uses an inclined plane to get a 50 kg box into the boot of her car. If the boot is 1 m high and the inclined plane is 3 m long. What is the force she has to apply.