Newton's force and circular acceleration

In summary: It is always a good idea to double check with your professor to make sure you understand the problem correctly. Keep up the good work!
  • #1
homo-sapiens
28
0

Homework Statement



Your niece finds her father's watch. The light watch chain has a length of 35 cm, and the mass of the watch is 190 g. Your niece swings the watch in a vertical circle, maintaining the speed of the watch at 2.4 m/s. Find the tension in the chain when it makes an angle of 43° with respect to the vertical. (Assume the watch is closer to the top of the circle than the bottom. Also assume the radius of the circle is 35 cm.)

Homework Equations



F=ma
a=v^2/r

The Attempt at a Solution



I drew free body diagrams, balanced the forces and derived at an equation. The answer I got was 1.765 Newton which was incorrect. Can someone please tell me what mistake I made??

http://puu.sh/bMw81/df16b4f7f9.png [/B]
 
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  • #2
your work looks good but watch significant figures. Try 1.8 N.
 
  • #3
i am pretty sure, sig fig doesn't matter to the website, because i have submitted answers which definitely has wrong sig figs but is still marked correct. thanks for the advice though, need to be careful of sig figs on tests and exams.
 
  • #4
homo-sapiens said:
i am pretty sure, sig fig doesn't matter to the website, because i have submitted answers which definitely has wrong sig figs but is still marked correct. thanks for the advice though, need to be careful of sig figs on tests and exams.
I think your answer is correct.I have checked the calculation too.
 
  • #5
http://puu.sh/bMPIE/b03325effc.png
I guess I should check with my prof about it.
thanks for the reaffirmation
 
Last edited by a moderator:
  • #6
homo-sapiens said:
http://puu.sh/bMPIE/b03325effc.png
I guess I should check with my prof about it.
thanks for the reaffirmation
You are welcome.
 
Last edited by a moderator:

FAQ: Newton's force and circular acceleration

1. What is Newton's second law of motion?

Newton's second law of motion states that the acceleration of an object is directly proportional to the net force acting on the object and inversely proportional to its mass. In other words, the greater the force applied to an object, the greater its acceleration will be, and the more mass an object has, the less it will accelerate.

2. How does circular motion relate to Newton's second law?

In circular motion, an object is constantly changing direction as it moves along a curved path. This change in direction is due to a force acting on the object, which is known as centripetal force. According to Newton's second law, this force must be directed towards the center of the circle and be equal to the mass of the object multiplied by its centripetal acceleration.

3. What is centripetal acceleration?

Centripetal acceleration is the acceleration towards the center of a circle that an object experiences while moving in a circular path. It is always perpendicular to the object's velocity and is directly proportional to the square of its speed and inversely proportional to the radius of the circle.

4. What is the relationship between force and circular acceleration?

The force required to keep an object moving in a circular path is directly proportional to the object's mass, speed, and the radius of the circle. This means that as any of these variables increase, the force required to maintain circular motion also increases. This relationship is described by the equation F = ma, where F is the centripetal force, m is the mass of the object, and a is the centripetal acceleration.

5. How does centripetal force affect the velocity of an object?

Centripetal force only affects the direction of an object's velocity, not its magnitude. This means that the speed of an object moving in a circular path will remain constant, while its velocity constantly changes direction. This is because the net force acting on the object is always directed towards the center of the circle, which only changes the direction of motion, not the speed.

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