Embibe Experts Solutions for Chapter: Force and Laws of Motion, Exercise 1: Exercise

Crumple zone is a new structural safety feature that has been widely applied in various types of cars. The application of the crumple zone is to help absorb energy from the impact of a collision that controls deformation. The front crumple zone of a car is tested at a road traffic laboratory. This is done by using a remote control device to drive the car into a strong barrier. Electronic sensors are attached to the dummy inside the car.

At the point of collision, the car exerts a force of $5000 \mathrm{N}$ on the barrier. State the size and direction of the force exerted by the barrier on the car.

Suggest why the dummy is fitted with electronic sensors.

A roller-coaster car stops above a vertical drop. Suddenly it falls under gravity. The drop is $60$metres high and at the bottom of the drop the car travels at $125 \mathrm{km}/\mathrm{h}$. The acceleration experienced by the people in the car is $10 \mathrm{m} {\mathrm{s}}^{-2}$. The mass of the car and its passengers is $1210 \mathrm{kg}$. Calculate the force exerted on the car and its passengers. 

A crane is used to lift a steel girder to the top of a high building.

A motor is fitted to the crane. This motor accelerates the girder at $0.3 \mathrm{m} {\mathrm{s}}^{-2}$. Calculate the force which the crane applies to the girder to produce this acceleration.

When a gun is fired, a very large force acts on the bullet for a very short time. An average force of $4000 \mathrm{N}$ acts for $0.01 \mathrm{s}$ on a bullet of mass $50 \mathrm{g}$. Calculate the speed of the bullet.

Srikanth Kidambi is an excellent Indian badminton player who represented India in Rio Olympics. The diagram shows him in between a match.

The shuttlecock weighs very little. When you drop it from a height of a few metres, it accelerates at first but soon reaches a steady speed.

Explain, why the shuttlecock accelerates at first, and why the shuttlecock reaches a steady speed.