Question

DAU COROANA PLS E URGENT

Answer 1

2.  n1sini = n2sinr    n2 = n1sini/sinr =( √2 /2) /(1/2) = √2
3.  f  = - 40cm    x1/x2 = 2/1    x1 = 2x2
-1/f = 1/x2 - 1/x1
-1/40 = 1/x2 - 1/(2x2)    -1/40 = 1/(2x2)      x2 = -20cm    x1 = - 40cm
4.  L = F·d·cosα  = 10·4·1/2 = 20J
5.  v1 = 20m/s
d/2 = v1·t1     t1 = d/(2v1)
d/2 = v2·t2     t2 = d/(2v2)    t1 + t2 = (1/v1 + 1/v2)·d/2 = (v1+v2)·d/(2·v1·v2)
Vm = d/t = d/(t1+t2) = d·2·v1·v2/[d(v1 + v2)] = 2·20·40/60 = 80/3 m/s =
80/3 ·3600/1000 = 96Km/h
6.  la inaltimea h:  E = Ep + Ec = mgh + 0 = mgh
la inaltimea h/4 : E = mgh/4 +Ec    Ec = mgh - mgh/4 = 3mgh/4
Ec1/Eci ·100 = (3mgh/4)/mgh·100 =  75%