Answer in short. Q1.Give an example of a situation where work done is zero? Q2.Give two uses of an inclined plane? Q3.Give some examples examples where pulley is used as a simple machine? Q4. What is the lead of a screw? Q5. Why do we use a wedge? Q6. Define input energy and output energy?
Answers
Answer:
1).POSITIVE WORK :the work done on an object is said to be positive work when force and displacement are in same direction.
example: When an object moves on horizontal surface,force and displacement acts in forward direction. So,work done is positive.
NEGATIVE WORK:The work done is said to be negative work when force and displacement are in opposite direction.
example: When an object is thrown upwards,the force CTS in downward direction whereas displacement acts in upward direction.
ZERO WORK:The work done is said to be zero work when force and displacement are perpendicular to each other or when either force or displacement is zero.
example: When we hold an object and walk,the force acts in downward direction whereas displacement acts in forward direction.
2).A ramp is an example of an inclined plane. Using an inclined plane makes it easier to move an object. It takes less force to move an object in an upward direction on an inclined plane than it does to lift the object straight up. ... It would take more force to move a load up this steep incline.
3).Sails on sailboats are raised and lowered using pulleys. Garage doors raise and lower utilizing a pulley system. Rock climbers use pulleys to help them to climb. Timing belts in cars are examples of pulleys.
4).Lead is the axial advance of a helix or screw during one complete turn (360°) The lead for a screw thread is the axial travel for a single revolution. Pitch is defined as the axial distance between adjacent threads on a helix or screw.
5).Use of a wedge
Wedges are used to lift heavy objects, separating them from the surface upon which they rest. ... This is the mechanical advantage of the wedge.
6).Input energy' is the amount of energy going into a system. 'Output energy' is the amount of energy going out of a system.