00:02
For letter a, we need to find the final speed of the sprinter in the problem.
00:09
So we're given the mass of the sprinter, which is 70 kilograms, the net force, which is 650 newton's, and the time interval, which is 0 .80 second.
00:28
To solve this, we will use the second law, newton second law equation, which is 7 .000 .2nd.
00:34
Mission f equals mass times the acceleration so you may ask where's the velocity in this equation actually we can replace a here with the uniformly accelerated motion or ua m equation for acceleration which is so acceleration equals v sub 2 or final velocity minus v sub 1 or initial velocity over the time interval so hence, so if you substitute this equation and the newton second law equation, our equation would be, so summation, f equals mass times the acceleration equation, which is v2 minus v sub 1 over the time interval.
01:31
So simplifying the equation, so this will become, so the left -hand side would be summation f times the time interval equals, so distribute the mass inside the parentheses, so m v -2 minus m, v -1.
01:49
So since we need v -sub -2, the final speed or the final velocity, so we have to leave it on one side of the equation, so we have to.
02:01
Transfer negative m v sub 1 to the other side.
02:06
So we'll have m v.
02:08
2 equals summation f delta t plus m v .1...