Answer :
1) a and c
2) d
3) change in momentum of the body = 2 kg (0 - 4)m/s = - 8 kg-m/s
friction force = change in momentum / duration = (-8 kg-m/sec ) / 2 sec
= - 4 Newtons
force needed to maintain the uniform velocity of 4 m/s from the beginning is
= + 4 Newtons, in the direction of movement of the body.
2) d
3) change in momentum of the body = 2 kg (0 - 4)m/s = - 8 kg-m/s
friction force = change in momentum / duration = (-8 kg-m/sec ) / 2 sec
= - 4 Newtons
force needed to maintain the uniform velocity of 4 m/s from the beginning is
= + 4 Newtons, in the direction of movement of the body.