What does the velocity term 'per second, per second' mean?

Question

To clarify: a standard size ball (e.g. tennis ball) dropped by a person on earth will apparently travel at approx. '9.8 metres per second, per second'. What does the second 'per second' mean? Is that just another way of saying that every passing second a further 9.8 metres has been travelled? If so, that's just a tautology and makes the meaning of the term unclear.

Help please - I'm confused!

Answer 1

Say the ball or whatever starts with some initial velocity. As it falls, its speed will increase by 9.8 meters per second, every second. I other words, the ball gets faster as it falls and this is how many meters per second it adds every second.

Answer 2

Listen mate, first let's clear the core of the confusion, the term which you're referring to as velocity term is actually an unit for acceleration. Velocity and acceleration are different terms.

I hope you would understand the difference between velocity and acceleration. Velocity is measured in terms of m/s( meters per second, feet per second etc.) ; velocity is a measure of how much distance an object travels within a unit time, also in a specific direction ( like in x meters/ sec velocity implies that the object has travelled x meter in 1 second)

while acceleration is measured in terms of m/s^2, ( meters per second square, or feet per second square); and is considered as a parameter for measuring change of speed within a unit time. e.g. y meters per second per second ( or meters per second square), means the object is gaining velocity of y meters/second in every second of it's travel.

for example, if an object is falling under gravity , which is a force acting on the object, this force will cause the object to change it's velocity every second, this change of velocity is coined as acceleration ( in this case acceleration due to gravity)

So, if you let go a stone off your hand from ,say, 5th floor of a building , it's velocity will increase 9.8 meters /second ( remember unit of speed) for every second it travel towards the ground, not that it will pass 9.8 meters further- which you're implying

Basically, it's like rephrasing the object will gain an extra amount of 9.8 m/sec of velocity in every ( per)second.;

I hope it may be of some help for your query.

Answer 3

The size or mass is not relevant. Every object falls the same way, if the friction by the air can be ignored.
Every second the speed of a falling object increases with 9.8 m/s.
So the acceleration is (9.8 m/s)/s = 9.8 m/s/s = 9.8 m/s2

Th

Answer 4

My physics may be a bit rusty, but here goes. 32 feet per second per second is the rate of acceleration of an object as it freefalls due to gravity. This acceleration is maintained until the terminal velocity for the objects mass has been reached. All objects will fall at this rate irrespective of mass.

Answer 5

It's acceleration that is per second per second. Acceleration is the rate at which velocity increases (or decreases if the acceleration is negative)

Velocity is just per second. It is the rate of change of displacement (how far the object is from a given point).

Answer 6

It's acceleration not velocity; Ig is normal gravity as far as we are concerned, and objects in 1g will accelerate by 32 feet per second per second. In other words, after each second the velocity will have increased by 32 feet per second.

Sorry, I'm pre-metric!

Answer 7

'per second, per second' is not a term for velocity. It is a term for acceleration. Let's say you are going 20 miles per hour. That's your velocity. You step on the gas and soon, in 20 seconds, you are going 60 miles per hour. Your acceleration was "40 miles per hour, per 20 seconds". Now, just change the units, which means change the miles per hour and the seconds to something else....40 mph per 20 sec is the same as 2 mph per second for example.
If you feel like you just MUST have "per second, per second" , just keep changing the units...in this example, change the mph to miles per second ...

Answer 8

It is a unit of acceleration due to gravity. Acceleration is measured in change in velocity per second. Per second per second is a bit pedantic but it does work.

xxB

Answer 9

m per sec per sec is m/s^2

that stands for the acceleration.
the velocity of body wld change by 9.8 m/s at each second,

After 2 secs ,vel =x
After 3 secs, vel =x +9.8
after 4 secs,vel =x +9.8 +9.8 ...and so on.

So velocity ic not constant but changes at a certain fixed rate.

Answer 10

I learned something today....here is a link also. Good question.