Chapter 4 - Section 4.2 - Newton’s First and Second Laws - Example - Page 58: 4.1

a) $3.1\ kN$ b) $5.6 \ kN$

We solve using known equations to find: a) $F = ma = m\frac{\Delta v}{\Delta t} = 1200kg \times \frac{20m/s}{7.8s}=3.1 \ kN$ b) $F = ma = m\frac{v^2}{r} = 1200kg \times \frac{(20m/s)^2}{85 m }=5.6 \ kN$