Mountain Climbing. Mountaineers often use a rope to lower themselves down the face of a cliff (this is called rappelling). They do this with their body nearly horizontal and their feet pushing against the cliff (Fig. P11.45). Suppose that an 82.0-kg climber, who is 1.90 m tall and has a center of gravity 1.1 m from his feet, rappels down a vertical cliff with his body raised 35.0 above the horizontal. He holds the rope 1.40 m from his feet, and it makes a 25.0 angle with the cliff face. (a) What tension does his rope need to support? (b) Find the horizontal and vertical components of the force that the cliff face exerts on the climbers feet. (c) What minimum coefficient of static friction is needed to prevent the climbers feet from slipping on the cliff face if he has one foot at a time against the cliff?

Vectors Position and displacement vectors Vector Addition and subtraction Velocity and acceleration vectors Multiplying vectors Vector and Scalar Vector: a quantity that has both magnitude and direction Scalar: a quantity that has only magnitude How to express a Vector: Graphical: An arrow with a magnitude and directions Components: a component of a vector is the projection of the vector on an axis; the x- component and the y-component. o Magnitude is the square root of x + y 2 Unit vectors: a vector that has a magnitude of 1 and points in a particular directions; it specifies only a direction. Position Vector The Location of a particle relative to the origin is given by a