1. What is tangent? 

     2. When a knife is been sharpening at a grind stone the direction of its spark are? 

A tradesman sharpens a knife by pushing it against the rim of agrindstone. The 50 cm diameter stone is spinning at 200 rpm and hasa mass of 18 kg. The coefficient of kinetic friction between theknife and the stone is 0.20.

If the stone loses 10 percent of its speed in 10 s of grinding,what is the force with which the man presses the knife against thestone?

A person stands in a stationary canoe and throws a 5.00-kg stone with a velcity of 8.00 m/s at an angle of 30.0 above the horizontal. The person and canoe have a combined mass of 105 kg. Ignoring air resistance and effects of the water, find the horizontal recoil velociy (magnitude and direction) of the canoe. Assume hte horizontal component of the velocity of the stone is in the +x direction.