You can feel a force of air drag on your hand if you stretch your arm out of the open window of a speeding car. Note: Do not endanger yourself. What is the order of magnitude of this force? In your solution, state the quantities you measure or estimate and their values.

The figure shows the configuration of two identical bricks. In case 1 the bricks are placed end to end. In case 2 the bricks are stack on top of each other. What can you say about the kinetic friction when the bricks are pushed across a tabletop with constant speed?

Many physical properties, such as force and mass, cannot be measured directly. Rather, some other physical property is measured and the desired physical property is computed from the results. For example, a bathroom scale does not actually measure mass or "weight," but rather the compression distance of a spring. The numerical values on the scale are calibrated from the compression distance using basic physics principles such as Newton's second law. Coefficients of friction cannot be measured directly. In this problem, we are going to learn how we can indirectly measure the coefficient of kinetic friction between two surfaces by directly measuring the expansion of a spring. Consider a 5.45 kg5.45 kg block that is dragged by a spring on a (relatively) frictionless horizontal surface at constant velocity. Suppose the block reaches a rough patch and the spring stretches by 5.25 cm5.25 cm. Compute the coefficient of kinetic friction ?μ between the block and the rough patch if the spring…

An 96kg  diver inhales to have a body density of 950 kg/m3, then swims to the bottom of a shallow sea (sea water density = 1024 kg/m3) and begins to float to the surface.  What is his acceleration? (g=9.8 m/s2)