Calculating Forces for Angles of 30, 45 & 60

In summary, the student attempted to solve a homework problem involving finding the weight of a block, normal force, and net force at different angles, but he made a mistake in his calculations. He corrected the mistake and was able to solve the problem correctly.
  • #1
pebbles
95
0

Homework Statement


angles of 30, 45, 60. calculate weight of block, the normal force, and net force for each angle separately.

Homework Equations


normal force m*g*sin theta
net force m*g*cos theta



The Attempt at a Solution


weight of block is just 20 kg, right?

and so for 30 degrees: normal force= 20 kg* 9.81 m/s/s * sin 30, right? and net force=20 kg * 9.81 m/s/s * cos 30...
 
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  • #2
No. The weight of an object is measured in lbs or N. kg is a unit of mass.

Weight in Newtons = mass in kg*acceleration due to gravity in m/s^2.

Draw a diagram showing all your forces.
 
  • #3
wait...my next question then asks how does each force value change as the angle changes and why?

in this case, wouldn't the weight be constant...?
 
  • #4
You're absolutely right. (weight is constant). Your calculations are not, however, correct.
 
  • #5
ok, then can you please tell me what i did wrong and how to calculate them correctly?
thanks.
 
  • #7
ugh. I'm still confused.
 
  • #8
Gm is the weight, N is the normal force. the Alpha sign is the angle. The same angle of the incline. Do you see that a triangle has formed? You can apply the trig functions of sine and cosine.
 
  • #9
so normal force= 196.2 N * cosine 30=170N, which is what I had,
and net force= 196.2 N *sin 30=98.1

?
 
  • #10
is that correct?
 
  • #11
You had normal force = 196.2sin30 which is not correct.

Now your calculations look correct. If there was friction then the net force would be the force going down the incline subtracted from the friction force(going up the incline).

But everything looks good! great job!
 
  • #12
right, i did have it like that and just now after i looked at my notes, i realized i accidently switched the two formulas.

thanks for your help. i really appreciate it!
 

What is the formula for calculating forces for angles of 30, 45, and 60?

The formula for calculating forces for angles of 30, 45, and 60 is F = m x a, where F is the force, m is the mass, and a is the acceleration. This formula is also known as Newton's Second Law of Motion.

How do I calculate the force for a specific angle of 30, 45, or 60 degrees?

To calculate the force for a specific angle of 30, 45, or 60 degrees, you will need to know the mass of the object and the acceleration. Once you have these values, you can plug them into the formula F = m x a to calculate the force.

What units are used to measure force?

The standard unit for force is Newtons (N). However, force can also be measured in other units such as pounds (lbs) or kilograms (kg).

Are there any other factors to consider when calculating forces for angles of 30, 45, and 60?

Yes, there are other factors to consider when calculating forces for angles of 30, 45, and 60. These include friction, air resistance, and the direction of the force relative to the angle.

Can I use the same formula to calculate forces for all angles?

No, the formula for calculating forces (F = m x a) is specific to angles of 30, 45, and 60 degrees. For other angles, you will need to use trigonometric functions such as sine, cosine, and tangent to calculate the force.

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