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. The velocity at which the horse can move by applying a force on the earth depends on the mass of the horse (and the cart attached to it). The heavier the cart, the slower the motion of the horse (for a given amount of force applied by the horse on the Earth). If the cart is too heavy, the force exerted by the horse on the Earth will be insufficient to even overcome the force of inertia. In this case, the horse will not be able to pull the cart.

Answered by Shivani Kumari | 2 years agoA motorcar of mass 1200 kg is moving along a straight line with a uniform velocity of 90 km/h. Its velocity is slowed down to 18 km/h in 4 s by an unbalanced external force. Calculate the acceleration and change in momentum. Also calculate the magnitude of the force required

A hammer of mass 500 g, moving at 50 m s^{-1,} strikes a nail. The nail stops the hammer in a very short time of 0.01 s. What is the force of the nail on the hammer

Two persons manage to push a motorcar of mass 1200 kg at a uniform velocity along a level road. The same motorcar can be pushed by three persons to produce an acceleration of 0.2 m s^{-2}. With what force does each person push the motorcar? (Assume that all persons push the motorcar with the same muscular effort)

**The following is the distance-time table of an object in motion:**

Time (seconds) |
Distance (meters) |

0 | 0 |

1 | 1 |

2 | 8 |

3 | 27 |

4 | 84 |

5 | 125 |

6 | 216 |

7 | 343 |

**(a)** What conclusion can you draw about the acceleration? Is it constant, increasing, decreasing, or zero?

**(b)** What do you infer about the forces acting on the object?

How much momentum will a dumb-bell of mass 10 kg transfer to the floor if it falls from a height of 80 cm? Take its downward acceleration to be 10 ms^{–2 .}