A 10.0 kg bowling ball is moving at 10 m/s when it strikes a 20 kg bowling pin. After the collision, the pin moves forward at 15 m/s. How fast is the ball moving after it hits the pin?

The ball moves backwards with a velocity of -20m/s

The data given are;

This law states that assuming no external forces are acting, when two bodies collide together, the sum of their initial momentum remains constant and it's not changed by their collision.

Applying the law of conservation of linear momentum

collect like terms

This shows that the balls moves backwards hence the reason why it have a negative velocity.

From the calculation above, the ball moves backwards with a velocity of -20m/s.

Learn more on conservation of linear momentum here;

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20 m/s

Explanation:

Given

mass of bowling ball m=10 kg

Mass of bowling pin M=20 kg

The initial velocity of ball u=10 m/s

The velocity of the pin after collision

Conserving linear momentum as there is no external force applied

i.e. ball started moving in the direction opposite of its initial direction with a velocity of 20 m/s

here we know that ball will drop down by total distance 3.2 m

so here we know that

now using kinematics

now in the same time it will cover horizontal distance of 0.75 m

so speed of the ball will be