A car travelling an unbanked curve of radius 200 ft notices a truckstopped on the road ahead. The driverimmediately applies brakes causing the speed of the carto decrease at the rate of 10 ft/s2. If at that instant, the stationary truckis 100 ft ahead (the distance is measured along the path) and the car is travelling at a speed of 40ft/s, whatis the magnitude of the relative velocity ofthe truck perceived by the driver of the car (i. e. from the moving frame of referenceof the car).

 u = - 40 ft / s

Explanation:

The Galilean relation for the relative velocity is

         v ’= v + u

where u is the speed between the two reference frames, v is the speed of the fixed system and v 'the speed of the mobile system.

In this case the truck has a speed with respect to the ground (fixed system) 0 m / s (it is stopped), the car has a speed with respect to the ground of v = 40 ft / s,

        u = v'- v

        u = 0 - 40

        u = - 40 ft / s

the speed perceived by the car if the system is fixed on it is -40 ft / s

it breaks and dirupture other materials and other sencews from the bottom