Free Body Diagrams and Vectors

Question

A student exerts a force of 72.0 N along the handle of a 196 N (gravitational force) lawn mower to push it

across the lawn at an angle of 39° with the horizontal.

a)

Draw a free-body diagram to help.

b)

Determine the normal force given to the lawn mower by the ground?

Answer 1

a) You should have at least 3 forces (friction wasn't mentioned, and we don't need it for this problem): downwards weight, upwards normal force, and apllied force at the angle 39° from horizontal.

b) Sum vertical components: ΣF_y = F_N - 196 - 72 sin 39° = 0, so F_N = 196 + 45 = 241 N.