Question

Define speed, velocity, and acceleration. Can an object change speed without accelerating? Can an object accelerate without changing speed? Why or why not?Imagine throwing a ball straight up into the air. Describe its speed, velocity, and acceleration as it goes up and then comes back down again. What, if any, forces are acting on the ball as it is in the air?Now imagine throwing the ball horizontally, like a pitcher pitching a baseball at a batter. Describe its speed, velocity and acceleration as it travels through the air. What forces act on a horizontally thrown ball after it is released?

Answer 1

Speed is a scalar quantity, one that requires only a magnitude (miles per hour, here). Velocity is a vector quantity, one that requires a magnitude (also mph) and a direction. Speed is a measure of distance traveled over a certain amount of time.

velocity is a different story since it measures displacement over time, as opposed to distance. Displacement is a measure of how far from the starting point an object ends up.Velocity is the rate of motion in a specific direction.

Acceleration is also a vector quantity, requiring both a magnitude and a direction. Acceleration is often called 'speeding up,' though it would more accurately be referred to as 'velocitying up!.' Still, to understand acceleration, it is probably easiest if we think about straight line acceleration, in which case speed and velocity are similar (since direction is not changed).

a = change in velocity / time

where, Change in velocity = final velocity - initial velocity = v -u

Can an object change speed without accelerating? No, Because if if speed of object changes than the object must be accelerating. Since, change in speed means change in velocity. and change in velocity means acceleration.

Can an object accelerate without changing speed? Yes, As in case of uniform circular motion, instead of constant speed it is called accelerated motion because direction of speed changes continuously. And change in direction means change in velocity. and change in velocity means acceleration.

when ball is thrown vertically up.

Forces acting on the ball will be gravitational force. in downward direction.

Its acceleration will be constant and will be equal to acceleration due to gravity. ( g = 9.8 m/s²)

Its speed and velocity decreases as it moves up and same will increase and it falls. here change in velocity/Speed will be constant.

When ball is thrown horizontally.

the only Forces acting on the ball will be gravitational force. in downward direction.

Its acceleration will be constant and will be equal to acceleration due to gravity. ( g = 9.8 m/s²) in downward direction. (vertical acceleration) and its horizontal acceleration will be zero because there is no horizontal force acting on the ball after release.

Similarly, its horizontal velocity and speed remains same and its vertical velocity increases as the ball decend towards earth surface.

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

Alright Dude, If that worked for you... dont forget to give THUMBS UP.(that will work for me!)

If I missed something feel free to leave a comment.
atleast before giving downvote.
and, Thanks for using homeworklib- Smarter way to study.