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DLS
 3 years ago
At the same instant that a 0.50kg ball is dropped from 25 m above Earth, a second ball, with a
mass of 0.25 kg, is thrown straight upward from Earth’s surface with an initial speed of 15 m/s.
They move along nearby lines and pass without colliding. At the end of 2.0 s the velocity of
the center of mass of the twoball system is:
DLS
 3 years ago
At the same instant that a 0.50kg ball is dropped from 25 m above Earth, a second ball, with a mass of 0.25 kg, is thrown straight upward from Earth’s surface with an initial speed of 15 m/s. They move along nearby lines and pass without colliding. At the end of 2.0 s the velocity of the center of mass of the twoball system is:

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DLS
 3 years ago
Best ResponseYou've already chosen the best response.1A. 11 m/s, down B. 11 m/s, up C. 15 m/s, down D. 15 m/s, up E. 20 m/s, down

mayankdevnani
 3 years ago
Best ResponseYou've already chosen the best response.1Since this is multiple choice, lets use 10 m/s^2 as the acceleration due to gravity.

mayankdevnani
 3 years ago
Best ResponseYou've already chosen the best response.1The trick is to look at the momentum of the system after 2 seconds. So for the heavy ball, after two seconds, it has a velocity of 20 m/s.

DLS
 3 years ago
Best ResponseYou've already chosen the best response.110+1.25/0.75 (wil we have a minus sign or are we considering just the mag?

mayankdevnani
 3 years ago
Best ResponseYou've already chosen the best response.1Thus it has a momentum of 10 kg*m/s.

mayankdevnani
 3 years ago
Best ResponseYou've already chosen the best response.1yaa, i took downwards negative. The light ball will have a velocity of 5 m/s (15 m/s going up minus 20 m/s due to gravity gives 5 m/s downward). So it has a momentum of 1.25 kg*m/s.

mayankdevnani
 3 years ago
Best ResponseYou've already chosen the best response.1In both cases, the negative sign indicates the momentum is downward, and the sum is 11.25 kg*m/s.

mayankdevnani
 3 years ago
Best ResponseYou've already chosen the best response.1Find the velocity of the system by dividing by the total mass (0.75 kg)?? then solve it and you get your answer.

DLS
 3 years ago
Best ResponseYou've already chosen the best response.1i took downwards positive and upwards negative,im getting something different

mayankdevnani
 3 years ago
Best ResponseYou've already chosen the best response.1no, always took downwards negative and upwards positive

DLS
 3 years ago
Best ResponseYou've already chosen the best response.1v=0+10*2 v=20m/s downwards and v=1520 v=5m/s upwards

mayankdevnani
 3 years ago
Best ResponseYou've already chosen the best response.1Find the velocity of the system by dividing by the total mass (0.75 kg) and you get 15 m/s down. so your answer is option C) 15 m/s up.

mayankdevnani
 3 years ago
Best ResponseYou've already chosen the best response.1no,, 15 m/s down.

DLS
 3 years ago
Best ResponseYou've already chosen the best response.1im taking downwards negative and upwards positive so for the 0.25 kg ball, v=15+20=35? we are taking upwards positive right
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