For the hose to eject water at high velocities, a force must be applied on the water (which is usually done with the help of a pump or a motor). Now, the water applies an equal and opposite force on the hose. For the fireman to hold this hose, he must apply a force on it to overcome the force applied on the hose by the water. The higher the quantity and velocity of the water coming out of the hose, the greater the force that must be applied by the fireman to hold it steady.

Answered by Shivani Kumari | 1 year 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 .}