if it takes 726 watts of power to move a mass 36 meters in 14 seeconds, what is the mass?
i really need like, step by step help please? asap.
thanks, michelle .
physics - bobpursley, Saturday, November 20, 2010 at 4:06pm
power= work/time= mass*g*distance/time
mass= power*time/distance*g
physics - michelle quendarsv, Saturday, November 20, 2010 at 4:24pm
so... would it be like,
726 x 14 / 36 ?
physics - bobpursley, Saturday, November 20, 2010 at 6:08pm
no, what happened to g (9.8m/s^2) in the denominator?
physics - michelle quendarsv, Saturday, November 20, 2010 at 6:40pm
but where did you get 9.8m/s2?
physics - Damon, Saturday, November 20, 2010 at 7:27pm
He is assuming that you are moving the mass up against gravity. g = 9.8 m/s^2
then force up = m g = 9.8 m
If you are moving it horizontally and there is no friction and it is stopped at the start, that is another problem entirely.
It has zero kinetic energy at the start and we need to find the KE at the end to find how much work is done.
we need the acceleration
36 = (1/2) a (14)^2
a = .367 m/s^2
then
v = a t = .367 *14 = 5.14
then (1/2) m (5.14)^2 = 726*14
However I suspect that the way bobpursley told you is what your teacher wants.
physics - Damon, Saturday, November 20, 2010 at 7:29pm
He is assuming that you are moving the mass up against gravity. g = 9.8 m/s^2
then force up = m g = 9.8 m
If you are moving it horizontally and there is no friction and it is stopped at the start, that is another problem entirely.
It has zero kinetic energy at the start and we need to find the KE at the end to find how much work is done.
we need the acceleration
36 = (1/2) a (14)^2
a = .367 m/s^2
then
v = a t = .367 *14 = 5.14
then (1/2) m (5.14)^2 = 726*14
However I suspect that the way bobpursley told you is what your teacher wants.
physics - michelle quendarsv, Saturday, November 20, 2010 at 8:03pm
That's a lot of work...
umm, it says nothing about "moving up against gravity"
but if you say so... thanks, i guess.
can you give me another example with this question
-What is the mass of an object if it took 270 J of work to move it 15 meters?
9.8 is g
If moving it up then
F = m g
F * distance = work = 15 m (9.8) in Joules
so
270 = 15 * m * 9.8
m = 270 / (15*9.8)
Okay, thank you...
I have another question
If an object has a mass of 47 kg and it is moved 27 meters in 60 seconds, how much power was used?
(also, would this also include the 9.8 from g?)
Thanks.
What's the answer
To find the mass of an object, we can use the equation: Work = Force * Distance.
In this case, the work done is 270 J and the distance moved is 15 m.
So, we can rearrange the equation to solve for force: Force = Work / Distance.
Substituting the given values, we have: Force = 270 J / 15 m = 18 N.
Now that we know the force, we can use Newton's second law of motion: Force = mass * acceleration.
Since the object is not accelerating (assuming constant speed), the acceleration is zero.
Therefore, we can conclude that the force acting on the object is due to gravity, which we can calculate using the equation: Force = mass * gravity.
Rearranging the equation, we can solve for mass: mass = Force / gravity.
Assuming gravity to be 9.8 m/s^2, we have: mass = 18 N / 9.8 m/s^2 = 1.84 kg.
So, the mass of the object is approximately 1.84 kg.
Please note that if the object is being moved horizontally and there is no friction, the work done to move it would solely depend on the force required to overcome friction, and the mass would not have any effect on it.