Question

A bicycle of 12 kg has its speed decreased from 12 ms ^-1 to 7 ms^{​​​​​-1} in 2.5 sec.

1. What is the direction of retarding force ?

2. What is the magnitude of force in Newton.

Answer 1

As the bicycle has decreased speed the retardation force is definitely opposite to the direction of motion.

v-u=at
=> a=(v-u)/t
=> a= -2 m/s2

magnitude of retarding force F=ma= -24N