C. Three isotopes of the same element because the number of electrons and protons remain the same but the number of neutrons in the nucleus are different. This means that the isotopes have different masses to each other but the same chemical properties.
The velocity of the girl is -4.8 m/s.
Using the principle of conservation of linear momentum, The total momentum of bodies before and after collision is constant. Since the two objects are stationary, the initial momentum of each body is zero.
Thus;
0 = (80 × 3) + (50 × v)
0 = 240 + 50 v
-240 = 50 v
v = -240/50
v = -4.8 m/s
Note that the negative sign shows that the velocity of the girl is in opposite direction that that of the girl.
Learn more about momentum: brainly.com/question/904448
Answer: The average velocity is 150 km/h
Explanation: 70+80=150
The direction is the same as the direction the ball is moving in. Because of the rolling of the ball, the direction of movement of the surface of the ball is opposite the overall direction of the ball. Since friction will oppose the direction of movement of the surface of the ball, it is in the same direction as the net direction of movement of the ball.
