ncert solutions physics class 11th

The motion is uniform when it moves in a straight line at a constant speed. There is no acceleration, and velocity remains constant over time. The non-uniform motion occurs when the object is accelerating or decelerating. In this case the velocity of the object changes which includes changes either in direction or magnitude or both. The uniform and non-uniform motion concepts help explain how in different scenarios, the forces act to change the motion of objects.

According to the law of conservation of momentum, the total momentum of an isolated system before and after an event remains constant if no external force acts on it. The event can be a collision. Momentum is the product of an object's velocity and mass. For example, in the case of a collision between two cars, if there are no external forces such as an external push or friction applied, the momentum before and after the collision will remain constant.

According to the class 11 physics laws of motion, static friction is stronger than kinetic friction. It is the frictional force that resists the motion initiation between two objects. The largest static friction is proportional to the normal force. When two objects are already in motion relative to each other, the frictional force acting between two objects is called kinetic friction. It depends on the nature of the surfaces in contact and it is generally less than static friction. In everyday motion, both types of friction play significant roles.

Momentum has both magnitude and direction and it is a vector quantity. The direction of the momentum is the same as the direction of the velocity. It quantifies the "quantity of motion" of an object and reflects how fast it is moving and how much mass the object has, the standard SI unit for momentum is kilogram-meters per second (kg m/s). A heavier object moving a the same velocity as the lighter object will have greater momentum. Also, an object moving at a higher velocity will have higher momentum than the same object moving at a lower velocity.

When all the forces act on a single object, a free body diagram (FBD) graphically represents these forces. It helps in analyzing the net effect of the forces by isolating the object from its environment. An arrow pointing in the direction of a force represents a force and its magnitude is also labeled. FBDs allow systematic application of Newton's laws and hence are crucial in solving mechanics problems. For example on an inclined plane, in a block, the FBD helps identify normal, gravitational, and frictional forces acting on the block.

Inertia is the body's inherent property to resist any change in its state of rest or motion. Newton's First Law of Motion says that unless an external force is applied to an object, it will not change its state (rest or motion). Hence, the first law of Newton defines inertia. It also says that if the mass of an object is more then the inertia will also be more. For example, a loaded truck is harder to push than an empty one due to the fact that a loaded truck has more inertia.