Question

Va rog frumos , daca poate cineva sa rezolve as fi foarte recunoscator .

Answer 1

v2=72 km/h=20 m/s

v1=54 km/h=15 m/s

t=1 min 40 s=100 s

F=80 kN=80000 N

m=1000 t=1000000 kg

v2=v1+at<=>20=15+100a<=>5=100a=>a=0,05 m/s^2

Vectorial:F+G+N+Fr=ma

Scalar:F-Fr=ma=>Fr=-ma+F=-0,05•1000000+80000=-50000+80000=30000 N=30 kN

Fr=30 kN