Compared with the force needed to keep a box to slide at constant velocity on a coarse surface, to start the box sliding usually needs

A block of mass m is placed on a rough surface inclined relative to the horizontal. The incline angle is increased until the block start to move. Show that you can obtain the coefficient of static friction μs by measuring the critical angle θ where slipping occurs.   fill in the boxes.

Problem-solving questions At the back of the leg, two muscles pull on the Achilles tendon to create an upward force. Estimate the nett force if cach muscle has a diameter of about 5.0 mm and exerts a force in a direction of 25° from the vertical. (Use a force per unit area of muscle of 7x10° N/m²). An 18 kg penguin slides down an iceberg at an angle of 15° to the horizontal. Friction between the penguin's body and the ice surface is negligible. Determine the normal force acting on the penguin and its acceleration down the iceberg. A manufacturer of children's slides does some tests and discovers that the slope of a slippery slide must be at least 25° to the horizontal for the slide to work. The child involved in doing the testing weighs 35 kg. What is the coefficient of static friction between the child and the slide? A car drives onto a section of the road which is covered in ice. The driver attempts to stop by hitting the brakes but the wheels lock and the car skids for another 60 m.…

4–35.Determine the compressive loads in members AB and BC in Figure P4–35. 15" Bl 7" 8" 160 lb A FIGURE P4-35