## Rectilinear Kinematics: Continuous Motion| Engineering Mechanics| Dynamics| RC Hibbeler| Problem 12.1

A baseball is thrown downward from a 50-ft tower with an initial speed of Determine the speed at which it hits the ground and the time of travel. SOLUTION: $latex v_2^2=v_1^2+2a_c\left(s_2-s_1\right)&s=2&fg=000000$ $latex v_2^2=\left(18\right)^2+2\left(32.2\right)\left(50-0\right)&s=2&fg=000000$ $latex v_2=59.532\:ft/s&s=2&fg=000000&bg=8DB600$   $latex v_2=v_1+a_ct&s=2&fg=000000$ $latex 59.532=18+32.2\left(t\right)&s=2&fg=000000$ $latex t=1.29\:s&s=2&fg=000000&bg=8DB600$

## Newton’s Second Law of Motion: Concept of a System| Dynamics: Force and Newton’s Laws of Motion| College Physics| Openstax| Problem 1

A 63.0-kg sprinter starts a race with an acceleration of 4.20 m/s^2 . What is the net external force on him?