During strenuous exercise, it is possible to exert forces to the joints that are easily ten times greater than the weight being supported. What is the maximum force of friction (in N) under such conditions? (The frictional forces in joints are relatively small in all circumstances except when the joints deteriorate, such as from injury or arthritis. Increased frictional forces can cause further damage and pain.) she exert 67.0 kg of her mass on that knee?

An incline is tilted at an angle of 6.7° above the horizontal. A box of mass 34 kg is pushed up the incline with a force F along the incline. If the acceleration of the box is 1.1 m-s2, calculate the magnitude of F (in N) that is needed.

(a) Calculate the tension (in N) in a vertical strand of spiderweb if a spider of mass 8.00 x 10¯° kg hangs motionless on it. (Enter a number.) 0.000784 N (b) Calculate the tension (in N) in a horizontal strand of spiderweb if the same spider sits motionless in the middle of it much like the tightrope walker in the figure. 5.0° 5.0° T. TR w T. TR The strand sags at an angle of 15.0° below the horizontal. (Enter a number.) 0.046688914 X N Compare this with the tension in the vertical strand (find their ratio). (Enter a number.) (tension in horizontal strand) / (tension in vertical strand) =

Suppose you have a stack of 17 identical steel bars (steel bars have a mass of 1.00kg each). You are required to pull out bar number 16 from the stack (counting from the top of the stack down). Assuming that your assistant holds all other bars in place.   If the coefficient of friction between steel and steel is 0.750, how hard do you have to pull (in N)?

A 0.85 kg block of wood is stationary on an incline that is15◦above horizontal. A force of 3.0 N is being applied toit 75◦below horizontal, directly into the incline (the force isperpendicular to the incline). What is the minimum coefficientof static friction required to keep the block stationary?

A box of mass 5 kg is at rest on a rough plane inclined at an angle of 40° to the horizontal. Calculate the magnitude of the friction force, in newtons, to two significant figures. (Take the magnitude of the acceleration due to gravity, g. to be 9.8 ms 2.) The magnitude of the friction force is N (to 2.s.f.).

Zoologists have studied the mechanics of locust jumping. When a locust jumps, as depicted in the figure, the resultant force R exerted by the hind legs is the sum of two forces. The first force W acts directly downward to support the locust's weight, which is about 0.02 newton. The second force F is for the takeoff; its magnitude is about 0.29 newton, and the direction makes an angle of 55° with the horizontal. W 55° Find the magnitude of the resultant force R = F + W. (Use decimal notation. Give your answer to three decimal places.) magnitude of resultant force R: newton

The upper leg muscle (quadriceps) exerts a force of 1220 N , which is carried by a tendon over the kneecap (The patella) at the angle shown in figure 5.43. Find the magnitude and direction of the force exerted by the knee cap on the upper leg bone ( the femur ) . n? degree (counter clockwise from an axis directed to the left ) ?

Our 10.0-kg mystery box rests on a horizontal floor. The coefficient of static friction is 0.40 and the coefficient of kinetic friction is 0.30. Determine the force of friction, acting on the box if a horizontal applied force is exerted on it of magnitude: (a) 0, (b) 10 N, (c) 20 N Use 9.81m/s sqaured for the gravity and also F sub A unit for the applied force

What is the magnitude of the static friction force required to keep a 2.00 kg block resting on an inclined plane at an angle 25 degrees?  If the angle was increased, such that the incline plane was steeper, would the magnitude of the static friction force required to hold the block at rest increase, decrease, or stay the same?