A particle has velocity v(t)=t²−4t−5 m/s for t≥0. When does it come to rest?

Question

G1 Physics · Accepted Answer

Set v=0: t²−4t−5=(t−5)(t+1)=0, so t=5 s or −1 s. Since the motion is considered for t≥0, −1 s is not physically admissible. Therefore t=5 s.