Why does increasing concentration usually increase reaction rate

When you increase the pressure, the molecules have less space in which they can move. That will bring the molecules closer together and the reaction rate will increase. When you decrease the pressure, molecules don't hit each other as often and the rate of reaction decreases.

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b. lifting dumbbell weight at 20-degree angle from the body after a 45-degree angle

see the picture for the vector

the magnitude of the vector by pythagorean theorem

r = √( (-10)^2 + (3)^2 ) = √109

magnitude = √109 units

the direction angle between vector and x-axis is

tan^(-1)(3/10) = 16.699

so the direction is approximately 16.7 degrees north of west