It’s a snowy day and you’re pulling a friend along a level road on a sled. You’ve both been taking physics, so she asks what you think the coefficient of friction between the sled and the snow is. You’ve been walking at a steady 1.5 m / s, and the rope pulls up on the sled at a angle. You estimate that the mass of the sled, with your friend on it, is 60 kg and that you’re pulling with a force of 75 N. What answer will you give?
After drawing a free body diagram, as shown below, with the pulling tension force of the rope acting at a angle with the horizontal on the sled, the friction force , weight and normal reaction , we can project these forces on the vertical and horizontal axis and following Newton's first law have:
We can express the coefficient of friction as
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A large box of mass M is pulled across a horizontal, frictionless surface by a horizontal rope with tension T. A small box of mass m sits on top of the large box. The coefficients of static and kinetic friction between the two boxes are , respectively. Find an expression for the maximum tension for which the small box rides on top of the large box without slipping.