Помогите решить задания по физике, срочно

1
x(t) = 10*t - 2*t^2
v(t) = d/dt x(t) = 10 - 4*t
x(10) = 100 - 2*10000 = -20000+100 = - 19999

3
v(t) = v0 + a*t
v(0) = v0 = 20
v(5) = 0 = 20 + 5*a -> a = -4
v(t) = 20 - 4*t
x(t) = x0 + v0*t + 1/2*a*t^2
x(t) = 10 + 20*t - 2*t^2

4

h = h0 - 1/2*g*t^2 -> t^2 = 2*H/g = 2*25/9,81 = 50/9,81
t = 2.2576
v = gt = (2*H*g)^(1/2) = (50*9.81) )^(1/2) = 22

5
x1 = 5*t
x2 = 150 - 5*t
x1 = x2 -> 5*t = 150 - 5*t -> t = 15
x1(15) = 75
x2(15) = 150 - 75 = 75