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August 24, 2019, 06:03:29 am

Author Topic: Need help with these motion questions.  (Read 260 times)  Share 

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Etou

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Need help with these motion questions.
« on: December 19, 2018, 09:55:24 pm »
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I attached the questions, I need help completing them, don't need answers but what formulas to use etc.

insanipi

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Re: Need help with these motion questions.
« Reply #1 on: December 19, 2018, 10:27:05 pm »
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I attached the questions, I need help completing them, don't need answers but what formulas to use etc.
Hey there, that's a lot of questions!
Can you try to attempt these and show us your attempts before we try to help you out? ^-^

DinWell

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Re: Need help with these motion questions.
« Reply #2 on: December 19, 2018, 11:42:26 pm »
+5
I attached the questions, I need help completing them, don't need answers but what formulas to use etc.
Hey I'll give the formulas.
2. Newtons law is all you need. F = ma.
3. use the formula Fnet = mv^2/r to get magnitude of the net force. The direction will be towards the centre of the circular path.
4. Use F = mv^2/r and solve for v.
5. Remember that the tension of the rope has to counteract the force of gravity so the vertical component of the rope's tension is the same as the force of gravity on the ball (but opposite in direction). then use trigonometry to get the hypotenuse magnitude i.e. tension of string. You can use trigonometry to get the horizontal component of the tension. Then sub that into the circular motion eq. F = mv^2/r and solve for v.
1. since it says "uniformly", it constant acceleration so use suvat formula. From the information it gives, v^2 = u^2 + 2as is what you need.
once you get that, use newtons 2nd law to get net force. Fnet = ma
then, the sum of the force from the tow vehicle and the friction force = fnet (make sure you get directions correct). so sub in the friction and fnet to get the force from the tow vehicle.
« Last Edit: December 19, 2018, 11:46:49 pm by DinWell »
2018: English [???] | Methods [???] | Specialist [???] | Physics [???] | Chemistry [???]
2019: ???

Etou

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Re: Need help with these motion questions.
« Reply #3 on: December 20, 2018, 11:41:05 am »
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Hey I'll give the formulas.
2. Newtons law is all you need. F = ma.
3. use the formula Fnet = mv^2/r to get magnitude of the net force. The direction will be towards the centre of the circular path.
4. Use F = mv^2/r and solve for v.
5. Remember that the tension of the rope has to counteract the force of gravity so the vertical component of the rope's tension is the same as the force of gravity on the ball (but opposite in direction). then use trigonometry to get the hypotenuse magnitude i.e. tension of string. You can use trigonometry to get the horizontal component of the tension. Then sub that into the circular motion eq. F = mv^2/r and solve for v.
1. since it says "uniformly", it constant acceleration so use suvat formula. From the information it gives, v^2 = u^2 + 2as is what you need.
once you get that, use newtons 2nd law to get net force. Fnet = ma
then, the sum of the force from the tow vehicle and the friction force = fnet (make sure you get directions correct). so sub in the friction and fnet to get the force from the tow vehicle.

These are my answers:
1. a) 0.75 m/s/s b) 600N c) 1100N
2. a) 8 kg ---- Not sure what to do for b and c
3. D. and 2400N
4. 17 m/s
5. a) 1.18N b) not sure

Can you explain the uncompleted ones further and see if I got them correct?