ADVANTAGES OF FRICTION
• Friction between our feet and the ground stops us from slipping backwards. Thus, friction makes it possible for us to walk.
• We find it hard to walk on ice or on smooth, polished floor as movement across these surfaces produce less friction. That is why; we often slip on icy ground or wet floor.
DISADVANTAGES OF FRICTION
• Heat produced due to friction causes damage to machine parts such as car brakes.
• Friction causes damage to tyres of vehicles.
• Work is said to be done when a force applied on an object causes it to move in the direction of the force.
Work = force × distance
• We can measure work by measuring how much force, or energy, is required to move something, and multiplying that by how far it moved.
• Activities like sleeping, thinking, reading, etc. are not considered “work” in science.
• But, activities like playing sports, riding a horse, etc. are considered “work” in science.Read More...
• The ability to do work is called energy.
• There are many forms of energy.
• The energy which is possessed by an object due to its motion or its stored energy of position is called mechanical energy.
• Mechanical energy can be either kinetic energy (energy of motion) or potential energy (stored energy of position).
For example:Read More...
TYPES OF SIMPLE MACHINES
• A tool that makes our work easier by helping us overcome a larger force (load) by applying lesser force (effort) is called a machine.
• Machines may be simple or complex.
• A simple machine uses a single applied force (effort) to overcome a single force (load).
Figure 42: Types of simple machines
• A complex machine consists of two or more simple machines working together.