What is the magnitude of the net acceleration of the object

In summary, the conversation revolves around a student struggling with physics problems related to forces and acceleration. They seek help in understanding the concept and solving practice problems. One problem involves finding the net acceleration of an object with two forces acting on it, while the other involves finding the tension in a cable supporting a weight in equilibrium. The conversation concludes with the student getting the correct answers with the help of hints and diagrams.
  • #1
tsoya
11
0
im studying for a test, unfortunately i seem to be having difficulty with the simple problems, so i decided to try some practice problems:
1. two forces, each of 100N, act on an object having a mass of 40 kg. What is the magnitude of the net acceleration of the object if one of the forces is directed upward and the other is to the left?
the answer it says is 3.5 m/s^2. i know net external force=mass x acceleration, so i tried figuring out the net external force and I think that's where I get confused. because force is mass times acceleration? ug i don't know. can someone help please?
*******
oh thank you so much! i got it now, square root of (100^2 + 100^2) then divide by 40. may i ask another one?

a 250-N weight is suspended in equilibrium by two cables. one cable applies a horizontal force to the right. the other cable applies a force upward to the left at an angle of 45 deg. to the negative x-axis. what is the tension in the second cable? answer: 350 N
-how do you incorporate the first cable into figuring out for the second? I've tried solving this a couple of days ago, and still can't. any type of hint would be helpful!
 
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  • #2
First find the net force by adding the two force vectors to get their resultant. (Remember to use vector addition.) Then use Newton's 2nd law to find the acceleration.
 
  • #3
i posted another problem in the first post if anybody is willing to offer any help =)
 
  • #4
tsoya said:
a 250-N weight is suspended in equilibrium by two cables. one cable applies a horizontal force to the right. the other cable applies a force upward to the left at an angle of 45 deg. to the negative x-axis. what is the tension in the second cable? answer: 246 N
-how do you incorporate the first cable into figuring out for the second? I've tried solving this a couple of days ago, and still can't. any type of hint would be helpful!
Hint: Consider the vertical components of the forces. Since the object is in equilibrium, the net force on it must be zero. (Note that the first cable doesn't contribute to the vertical forces.)
 
  • #6
Ok, if we just consider the vertical components we can effectively ignore the horizontal cable as Doc Al said. Now, what force(s) are acting to pull the weight down and how big is this force?
 
  • #7
gravity is pulling it down (9.8, so total force is 250 N?)ok the answer is given to be 350, is that right?
 
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  • #8
Nearly right, what is the equation of force (one of Newton's laws)?
 
  • #9
force= mass x acceleration
 
  • #10
Yes, so what is the total force acting down?
 
  • #11
25.5 kg x 9.8 m/s^2= 250 N
 
  • #12
Yes, so as the system is in equilibrium that force must be balanced by an upward force. However, this upward force can only act through the angled cable. Draw a free body diagram, showing the weight, the downward force, the required upward force acting straight up and the angled wire.
 
  • #13
oh is this correct?:
250/(cos45)
i get a bit higher than 350 though, 353.55
 
  • #14
Yes, that is the answer which I got.
 
  • #15
thank you very much for all of your help =)
 
  • #16
No problem. For these types of problems I suggest drawing a diagram as it makes things a lot simpler.
 

FAQ: What is the magnitude of the net acceleration of the object

1. What is the definition of "magnitude of the net acceleration"?

The magnitude of the net acceleration refers to the numerical value of the overall acceleration of an object, taking into account both its speed and direction.

2. How is the magnitude of the net acceleration calculated?

The magnitude of the net acceleration can be calculated by taking the square root of the sum of the squares of the object's acceleration in each direction. This can be represented mathematically as |a| = √(ax² + ay² + az²), where ax, ay, and az are the accelerations in the x, y, and z directions, respectively.

3. What units are used to measure the magnitude of the net acceleration?

The magnitude of the net acceleration is typically measured in meters per second squared (m/s²) in the International System of Units (SI). However, other units such as feet per second squared (ft/s²) or kilometers per hour squared (km/h²) may also be used.

4. How does the magnitude of the net acceleration affect an object's motion?

The magnitude of the net acceleration directly affects an object's motion by determining how quickly its speed and direction will change. A larger magnitude of net acceleration will result in a faster change in motion, while a smaller magnitude will result in a slower change.

5. Can the magnitude of the net acceleration be negative?

Yes, the magnitude of the net acceleration can be negative. This indicates that the object is accelerating in the opposite direction of its initial motion. However, the magnitude itself is always a positive value, as it represents the numerical size of the acceleration regardless of direction.

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