25a) Cathy takes the bus home from work. In her hand she holds a 2 kg cake box tied together with a string. As she ascends the steps into the bus, the box accelarates at a rate of 2.5 m/s^2. What is the force exerted on the sting?
b) Cathy sets the box on the seat beside her. The bus accelarates from rest to 60 km/h in 4.0 s, and then the box begins to slide. What is the coefficient of static friction between the box and the seat of the bus.
c) A taxi suddenly cuts in front of the bus causing the bus driver to slam the brakes. The bus driver reduces speed from 60.0 km/h to 20 km/h in 1.5s. Does cathy's cake slide forward.
The Attempt at a Solution
I am done with A
but help with b and c will be really appreciated