Question

1. Find the pressure exerted on the ground (in psi) by a 250 lb person who is sitting on a chair whose 4 legs touch the ground with area of '1 by2' each.

2.a)A large 50 kg crate is at rest on level ground. Two people push on the crate. One pushes north with 200 N while the other pushes South with 50 N. If there is no friction, draw a diagram of this object labeling all forces with names and values.

b) Find the acceleration and direction of acceleration for the crate.

Answer 1

1.250 lb=113.4 kg.
mg =113.4•9.8 =1111.32 N.
A =1•2=2 sq.in =0.0013 m²
P=mg/4A =1111.32/4•0.0013 =213715 Pa
2.
The forces acting on the crate are:
F1, F2, gravity (downwards), normal force N (upwards)
Net horizontal force is
F=F1-F2 =200-50 = 150 N (to the North)
a=F/m=150/50 =3 m/s²(to the North).