The image above shows a block pulled across a table. The spring scale which measures in Newtons, reads the force resisting the motion known as friction force. In the image above, what would be a reasonable measurement of normal force if friction force
measured 80 Newtons?
A)
40 Newtons
B)
60 Newtons
70 Newtons
D)
140 Newtons

An alpha particle with kinetic energy 12.5 mev makes a collision with lead nucleus, but it is not "aimed" at the center of the lead nucleus, and has an initial nonzero angular momentum (with respect to the stationary lead nucleus) of magnitude l = p0 b, where p0 is the magnitude of the initial momentum of the alpha particle and b=1.40×10−12 m. (assume that the lead nucleus remains stationary and that it may be treated as a point charge. the atomic number of lead is 82. the alpha particle is a helium nucleus, with atomic number 2.) what is the distance of closest approach?