Difference between velocity and speed.

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SUMMARY

The discussion clarifies the distinction between speed and velocity using a tennis ball example. The ball, with a mass of 10.0 g, strikes the floor at 20.0 m/s and rebounds at 15.0 m/s. The change in speed is calculated as Δv = 5 m/s, while the change in velocity is Δv = 35 m/s, highlighting that speed is a scalar quantity without direction, whereas velocity is a vector quantity that includes direction. This fundamental difference is crucial for understanding motion in physics.

PREREQUISITES
  • Understanding of scalar and vector quantities
  • Basic knowledge of physics concepts related to motion
  • Familiarity with the equations of motion
  • Concept of momentum and energy conservation
NEXT STEPS
  • Study the principles of vector addition in physics
  • Learn about the equations of motion in one dimension
  • Explore the concept of momentum and its relation to velocity
  • Investigate real-world applications of speed and velocity in sports physics
USEFUL FOR

This discussion is beneficial for physics students, educators, and anyone interested in understanding the fundamental concepts of motion, particularly in the context of sports dynamics and mechanics.

Sirsh
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A tennis ball of mass 10.0 g bounces vertically on a concrete floor. The ball strikes the floor at 20.0 m s–1 and rebounds at 15.00 m s–1.

5.
A. What is the change in speed of the ball as it bounces?

Δv = v1-v2
= 20ms-1 - 15ms-1
Δv = 5ms-1

B. What is the change in velocity of the ball as it bounces?

Δv = v1 - v2
= 20ms-1 – (-15ms-1)
Δv = 35ms-1


Does that depict the difference between speed and velocity as speed is a scalar quantity it doesn't have direction therefore when calculating (in this case) is a positive value, but when calculating the change in velocity because it is a vector quanitiy it has a direction ( negative because it's going in the opposite direction as the initial drop) so it has a negative value? I am not sure if this is correct. thank you.
 
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You know it well, velocity is a vector quantity and speed is its magnitude, so a non-negative scalar. Well done!

ehild
 
Awesome, thank you (:
 

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