Many do not realize but we use couple forces every day.
When an equal amount of force acts about a point of pivot in the opposite direction at different points then this force is called couple force or just a couple.
When you try to open your water tap. Your use and thumb and finger to push the nob in the opposite direction.
Another daily life example is when you’re driving a vehicle like a bike or a car. You provide a couple to the handle or the steering wheel to turn your vehicle.
The next time you do to a cycle repair shop carefully observe the mechanical air pump they use. You would notice that the mechanic applies force on both sides of the pump handle to press it. It is a very good example of parallel forces.
When forces act in the same direction on the body then these forces are called parallel forces.
Do a small exercise. Take a piece of paper and write daily life application of couple forces and parallel forces.
Beyblade is a toy that uses the concept of couple and torque. When you pull the thread the teeth in the thread turn the gear inside the handle which in turn rotated the part which is mounted on a Beyblade. That amount applies torque on the Beyblade. The more torque supplied through the thread the faster the Beyblade would rotate.
Think of ways in which you can improve the launcher and try out different ideas.