If action is always equal to the reaction explain how a horse can pull a cart

• A horse pushes the ground in a backward direction. • According to Newton’s third law of motion, a reaction force is exerted on the horse in the forward direction. • When the horse walks in the forward direction (with the cart attached to it), it exerts a force in the backward direction on the Earth. • An equal force in the opposite direction (forward direction) is applied on the horse by the Earth. • This force moves the horse and the cart forward. As a result, the cart moves forward.

In the following example, try to identify the number of times the velocity of ball changes: “A football player kicks a football to another player of his team who kicks the football towards the goal. The goalkeeper of the opposite team collects the football and kicks it towards the player of his own team”. When a moving bus brakes to a stop, the lower part of our body which is in contact with the bus comes to rest while the upper part of our body tends to keep moving due to inertia of motion. Hence, one tends to fall forward. When the bus accelerates from rest, the lower part of our body comes into motion alongwith the bus while the upper part of body tends to remain at rest due to inertia of rest. Therefore, we fall backwards. The horse pulls the cart with a force (action) in the forward direction. The cart also pulls the horse with an equal force (reaction) in the backward direction. This way, the two forces get balanced. The horse pushes theground with its feet in the backward direction, while pulling the cart. So, the reaction of earthmakes it move in the forward direction alongwith the cart.

Views: 6,034 F = b t acts on a block of mass m kept on a smooth horizontal surface. An identical block is kept on the first block. The coefficient of friction between the block is μ. The time after which the relative sliding between the block takes place is : (A) 2 m g / b (B) 2 μ m g (C) μ m g / b (D) None of these Views: 5,460 15 kg is placed over a frictionless horizontal surface. Another block of mass 10 kg is placed over it which is connected with a light string passing over two pulleys fastened to the 15 kg block. A force, F = 80 N, is applied horizontally to the free end of the string. Friction coefficient between two blocks is 0.6. The portion of the string between 10 kg block and the upper pulley is horizontal as shown in figure. Pulley, string and connecting rods are massless (Take g = 10 ms − 2 ). Using the above information, answer the following questions The magnitude of acceleration of the 10 kg block is Views: 5,725 m is projected with a horizontal velocity u = 5 ​ m / sec as shown in figure. In consequence of it, the ball moves in circular path in a vertical plane by the inextensible string which passes over a smooth fixed peg P. If the maximum angle that the ball swings in the left hand side is θ from vertical then ( g = 10 m / sec 2 ) − − Views: 5,775 1.5. If the object distance is decreased by 5 cm, the magnification of the real image is increased to 4 . Find the focal length of the concave mirror. 9. A man places a rectangular glass slab of thickness 9 ...