Question

An athlete runs on a track with a velocity of 20 km/hr and jumps into a car of mass 50 kg standing on the track. Calculate the velocity with which the car will start moving along the track, if the weight of the athlete is 50 kg.
PLEASE ANSWER FAST... I HAVE EXAM TMRW

Answer 1

Answer:

v = 1.875 m/s

Explanation:

Mass of man (m1) = 60kg            

Initial velocity of man (u1) = 18 km/h=18x5/18=5m/s

Final velocity of man (v1) = (v2) = v 

Mass of car (m2)= 100kg

Initial velocity of car (u2) = 0 (as it is in rest)

Final velocity of car (v2) = v

According to law of conservation of momentum,

m1u1 +m2u2 = m1v1 + m2v2

60x5 + 100x0 = 60 x v + 100 x v

300+0 = 160v 

v = 300/160

v = 1.875 m/s

Answer 2

Answer:

v = 2.78 m/s

Explanation:

`the velocity of athlete  [u 1] =20 km/h = 5.56 m/s

the mass of athlete [m 1] = 50 kg

the velocity of car [u 2] = 0

mass  of car  [m 2] = 50 kg

m 1 u  + m 2 u  = m 1 v + m 2 v

50*5.56 + 50*0 = 50* v + 50*v

278 + 0 = 50v +50v

278 = 100v

v= 278/100

v = 2.78 m/s