Newton's Laws Applications

Question

A contestant in a winter games event pushes a 43.0 kg block of ice across a frozen lake as shown in the figure below.

A person is pushing a block of ice to the right on the surface of a frozen lake. The person is applying force on the top-left corner of the block. The arrow representing the force vector F is shown to act diagonally downward from the shoulder of the person to the top-left corner of the block. This arrow is at an angle of 25° below the horizontal from the person's shoulder level.

The coefficient of static friction is 0.1 and the coefficient of kinetic friction is 0.03. (For each answer, enter a number.)

Calculate the minimum force F (in N) he must exert to get the block moving.

 __N

What is its acceleration (in m/s²) once it starts to move, if that force is maintained?

 __m/s²

Answer 1

Draw The free Body diagram

Minimum Force

F= 0.03 (Mg + FSin 25 )/ Cos 25

Plug in M= 43 , g=9.8

sin 25 = 0.42

Cos 25 = 0.91

F= 12.64 /.91 +0.013 F/0,91

F= 13.9 + 0.0143 F

0.98 F = 13.9

F = 13.9/.98 = 14.18 N

Effective Horizontal force = F Cos 25= Ma

14.18 Cos 25 = 43 a

Find a