Answer:The mass of ball B is 10 kg.
Explanation;
Mass of ball A = 
Velocity of the ball A before collision:
Velocity of ball A after collision=
Mass of ball B= 
Velocity of the ball B before collision:
Velocity of ball B after collision=



The mass of ball B is 10 kg.
The object that reaches the ground first is thebowling ball i think because it weighs heavier but when the tennis ball hits the ground it will bounce again and again till it stops and the bowling ball will just stop it wont bounce
Since we know that
Gravitational potential energy = mass × height ×gravity
then
GPE = 1.5 kg x 0.500 m x 9.8m/s^2
therefore
GPE = 7.35 J