Solving Physics Problem: 24.5N Brick on 30° Incline

In summary, the conversation involves a physics problem where a brick weighing 24.5N slides down an inclined plane and collides with a second brick weighing 36.8N. The conversation covers the calculations needed to find the speed of the brick at the bottom of the incline, the initial speed of the two bricks when they stick together, and the time it takes for the bricks to stop sliding on a frictionless surface. There is also a discussion on using the equations a = g*sin(theta) and vf = vi + at to solve the problem, with the final solution being to use F=ma and recalculating the acceleration to find the correct answer.
  • #1
DarkAnt
195
0
ok, this is very simple... I think. Unfortunately my physics book is useless.

A brick weighing 24.5N being released from rest on a 1.00M frictionless plane, inclined at an angle of 30 degrees. The brick slides down the incline and strikes a second brick (on a flat frictionless surface) weighing 36.8N

a) calculate the speed of the brick at the bottom of the incline.
b) if the two bricks stick together, with what initial speed will they move along?
c) If the force of friction acting on the two bricks is 5.0N, how much time will ellapse before the bricks slide before comming to rest?

I think I could do the problem myself if I knew how to do part A.

Any help would be very appreciated.
 
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  • #2
Here's a hint:

[tex] a = g \cdot sin(\theta) [/tex]

g is the acceleration of gravity

[itex]\theta[/itex] is the angle at which the plane is inclined.
 
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  • #3
ty ty ty ty!

using the no time equation i can find the final velocity! thanks again
 
  • #4
uh oh

In C I have to find time it will take for the bricks to stop and I can't figure it out.

I found that Vf = 3.13m/s when it slides down and when the bricks collide the velocity of the two bricks is 1.25m/s. I found that the coefficient of friction is .08

I think I should use the equation vf = vi + at but I don't have a... or do I and I am just missing it?

could a = 5m/s^s? no it isn't that.

how about using Ff = ma? that would make a = -.08 and thus make the time = 15.6 sec. that doesn't seem correct. A little help would be nice (Jimmy come back!)
 
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  • #5
Sorry I had to bail on you but I had to log off for awhile to take care of personal business. I also thought you had things under control. I didn't see your last posts until now. I would have thought someone else would have helped out. <shrug>

Your method for solving problem c is correct, you just need to recalculate your acceleration. F=-5N, m=6.25Kg
 
  • #6
thanks a ton jimmy :smile:

that brings up a good question, where was everyone else?!

jk, its all good. Thanks again
 
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  • #7
Anytime...:smile:
 

1. What is the formula for calculating the force of the 24.5N brick on a 30° incline?

The formula for calculating force on an inclined plane is F = mgsinθ, where F is the force, m is the mass, g is the acceleration due to gravity, and θ is the angle of the incline.

2. How do you determine the weight of the 24.5N brick on a 30° incline?

To determine the weight of the brick, we use the formula W = mg, where W is the weight, m is the mass, and g is the acceleration due to gravity. In this case, we would use the mass of the brick, which is 24.5N, and the value for g, which is approximately 9.8 m/s².

3. What is the normal force acting on the 24.5N brick on a 30° incline?

The normal force is the force that is perpendicular to the surface of the incline. In this case, the normal force would be equal to the weight of the brick, which we calculated in the previous question to be approximately 240.1N.

4. How can you calculate the net force on the 24.5N brick on a 30° incline?

The net force is the sum of all the forces acting on the brick. In this case, the only forces acting on the brick are the weight and the normal force. To calculate the net force, we can use the formula Fnet = Fw + Fn, where Fw is the weight and Fn is the normal force.

5. What is the acceleration of the 24.5N brick on a 30° incline?

To calculate the acceleration, we can use Newton's second law, which states that F = ma, where F is the net force and a is the acceleration. We can rearrange this equation to find a = F/m. In this case, we can use the net force we calculated in the previous question and the mass of the brick to find the acceleration, which would be approximately 2.45 m/s².

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