Question

A girl of mass 40 kg jumps with a horizontal velocity of 5 m/s on to a

stationary cart with frictionless wheels. The mass of the cart is 10 kg. The girl

and the cart both move off together in the same straight line. Calculate the

velocity with which the girl and the cart move. Assume that there is no

external unbalanced force working in the horizontal direction

Answer 1

Here,
m1=40kg (mass of the girl)
m2=10kg (mass of the cart)
v1=5m/s(initial velocity of the girl)
v2=0m/s(initial velocity of the cart)
M=(40+10)kg( combined mass of the girl and the cart)
=50kg
V=?(combined velocity of both girl and cart)

We know,
m1v1+m2v2=MV
=. 200+0=50V
=. 200=50V
=. V=200/50
=. V=4m/s

therefore, combined velocity of both girl and cart will be 4m/s.

Hope this may help you.Thank you.

Answer 2

Answer:

Mass of the girl = 40 kg

Mass of the cart = 3 kg

Velocity of the girl = 5 m/s

Velocity of the cart = 0 m/s

To Find :-

Velocity as the cart starts moving.

Solution :-

Firstly let's find the Mounmentum of girl

[P = mv]

Here,

P = Mounmentum

M = Mass

V = Velocity

P = 40 × 5

Hence, Mounmentum of girl is 200 kg m/s .

Now,

Let's add the Mounmentum of girl and cart

200 + 0 = 200 kg m/s

Let's find total mass

Total mass = 40 + 3 = 43 kg

Velocity=Mounmentum/mass

V = P/M

Velocity = 200/43

Hence :-

Velocity of cart is when start moving is 4.65 m/s.

@ananya