Question

Two balls A and B of masses 40g and 50g are moving at speeds of 40m/s and 30m/s respectively. If after colliding B starts moving with a velocity of 25m/s what is the velocity of A? Pls help and also tell me how to mark smone as brainliest so tht I can mark u tht

Answer 1

Let masses of ball A and B are denoted as  $m_{1} \ and\ m_{2}$

Let the initial velocities of A and B are denoted as  $u_{1}\ and\ u_{2}\ respectively$

Let the final velocities of A and B are denoted as $v_{1}\ and\ v_{2}\ respectively$

As per the question  $m_{1} =40\ gram$ = 0.04 kg

                                   $m_{2} =50\ gram$ = 0.05 kg

                                   $u_{1}=\ 40\ m/s$

                                   $u_{2} =30\ m/s$

                                   $v_{2} =\ 25\ m/s$

As per law of conservation of linear momentum, the total momentum before collision must be equal to the total momentum after collision.

The total momentum before collision=  $m_{1} u_{1} +m_{2} u_{2}$

                                                             = 0.04×40 + 0.05×30

                                                             = 1.6 + 1.5 kg m/s

                                                             = 3.1 kg m/s

The total momentum after collision will be = $m_{1} v_{1} +m_{2} v_{2}$

                                                                       = $0.04*v_{1} +0.05*25$

                                                                       = $0.04v_{1} +1.25\ kg\ m/s$

But we have initial momentum = final momentum

                    $3.1\ kg\ m/s=0.04v_{1} +1.25\ kg\ m/s$

                    $0.04v_{1} =1.85\ kg\ m/s$

                    $v_{1} =\frac{1.85}{0.04}\ m/s$

                           $=\ 46.25\ m/s$   [ans]

Answer 2

Answer:

1

Explanation:

Let masses of ball A and B are denoted as

�

1

�

�

�

�

2

m

1

and m

2

Let the initial velocities of A and B are denoted as

�

1

�

�

�

�

2

�

�

�

�

�

�

�

�

�

�

�

�

u

1

and u

2

respectively

Let the final velocities of A and B are denoted as

�

1

�

�

�

�

2

�

�

�

�

�

�

�

�

�

�

�

�

v

1

and v

2

respectively

As per the question

�

1

=

40

�

�

�

�

m

1

=40 gram = 0.04 kg

�

2

=

50

�

�

�

�

m

2

=50 gram = 0.05 kg

�

1

=

40

�

/

�

u

1

= 40 m/s

�

2

=

30

�

/

�

u

2

=30 m/s

�

2

=

25

�

/

�

v

2

= 25 m/s

As per law of conservation of linear momentum, the total momentum before collision must be equal to the total momentum after collision.

The total momentum before collision=

�

1

�

1

+

�

2

�

2

m

1

u

1

+m

2

u

2

= 0.04×40 + 0.05×30

= 1.6 + 1.5 kg m/s

= 3.1 kg m/s

The total momentum after collision will be =

�

1

�

1

+

�

2

�

2

m

1

v

1

+m

2

v

2

=

0.04

∗

�

1

+

0.05

∗

25

0.04∗v

1

+0.05∗25

=

0.04

�

1

+

1.25

�

�

�

/

�

0.04v

1

+1.25 kg m/s

But we have initial momentum = final momentum

3.1

�

�

�

/

�

=

0.04

�

1

+

1.25

�

�

�

/

�

3.1 kg m/s=0.04v

1

+1.25 kg m/s

0.04

�

1

=

1.85

�

�

�

/

�

0.04v

1

=1.85 kg m/s

�

1

=

1.85

0.04

�

/

�

v

1

=

0.04

1.85

m/s

=

46.25

�

/

�

= 46.25 m/s [ans]