# Physics but algebra problem

posted by on .

Having issue with algebra.

89N=ma
99N=m2a

would you do something like plugging one into the other such as.
a=89/m
99N=99/(2(89/m)

prob is when i get a fraction in the denominator i get confused can someone help me. I'm trying to find the mass. Which i will then convert into weight (N). N=mg.

Can someone help?

• Physics but algebra problem - ,

It doesn't look like there is a solution.
First equation:
89N = ma

Second equation:
99N = m2a

For the second equation, if you divide both sides by 2 you get:
99N/2 = m2a/2
49.5N = ma

The first equation says ma = 89N.
The second equation says ma = 49.5N

Assuming a is constant, there is no single value of m that satisfies both equations.

• Physics but algebra problem - ,

When you lift a bowling ball with a force of 89 , the ball accelerates upward with an acceleration . If you lift with a force of 99 , the ball's acceleration is 2.

I'm guessing a is 9.8 m/s since it's gravity.

I trying to figure out the weight w and acceleration a.

w=mg
a=F/m

• Physics but algebra problem - ,

Remember that the acceleration of the bowling ball is the NET force of your lifting and gravity.
So, the acceleration of your 89N lifting is:
a = (89N - mg)/m
where g is gravity.
Likewise for the 99N lift:
a = (99N - mg)/m

• Physics but algebra problem - ,

Prob is I not sure exactly how to do the algebra when I plug in the a. and doesn't the m just cancel out? 0_0

• Physics but algebra problem - ,

Let a = the acceleration for 89N
Let m = the bowling balls mass.
Let g = acceleration of gravity.
So, 2a is the acceleration for 99N.

Set up the equation that shows the 99N acceleration is 2 times the 89N acceleration:

2(89N - mg)/m = (99N - mg)/m
Solve for m.

• Physics but algebra problem - ,

260,000 Newtons sorry.

• Physics but algebra problem - ,

huh?? 260,000 Newtons?

• Physics but algebra problem - ,

Mia's post accidently went here. Ignore it.

• Physics but algebra problem - ,

I'm not sure how to do the algebra the m in the denominator is confusing me. 0_0 so sorry i'm so difficult i feel stupid. not sure how to solve for m.

• Physics but algebra problem - ,

No problem. That is why we are here. You are not being difficult or stupied at all. No one is born knowing this stuff.

Some more hints:
2(89N - mg)/m = (99N -mg)/m

Let's get rid of the denominator.
Multiply both sides by m to get:
2(89N - mg) = (99N - mg)

Multiplying out the left side:
178N - 2mg = 99N - mg

178N = 99N + mg

Subtract 99N from both sides:
79N = mg
So,
m = 79N/g

• Physics but algebra problem - ,

My mistake!
stupied = stupid
See, we all make errors.

• Physics but algebra problem - ,

So that's what i got buttt for some reason the acceleration doesn't match up for the mass i'm getting from it. Why I am having such a difficult problem. See when I do N=mg i am getting m=79/9.81. Prob is for acceleration for both those forces the equation N=mg isn't working so it's confusing me.

• Physics but algebra problem - ,

Where i am having a problem to....Do you have same prob James? Acceleration is stumping me.

• Physics but algebra problem - ,

Go back and look at the two acceleration equations posted above. Don't forget to include gravity.

for 89N:
a = (89N - mg)/m

m and g are known

for 99N;
a = (99 -mg)/m
The acceleration at 99N should be twice the 89N a.

• Physics but algebra problem - ,

Thanks so much!!!!

• Physics but algebra problem - ,

what is the average acceleration of a subway train that slows down from 12 meters/ second to 9.6 meters/ second in 0.8 seconds