Calculating Acceleration and Tension in a Rope and Pulley System

In summary: If the motorcycle is accelerating towards the ramp, the weight is also accelerating.Using the same m for both masses is going to be confusing. Use a different name for each different variable. guy: m = 950kgweight: m - mg =950kg guy: m = 950kgweight: m - mg = 950kgThe net force on the motorcycle is going to be 950N. The tension in the rope is going to be zero.
  • #1
PhysicsNoob76
10
0

Homework Statement


An environmentally-sensitive daredevil wants to use a large mass, a rope, and a pulley to accelerate toward ramp while his motorcycle is in neutral, as shown below. If friction is negligible, what will the acceleration of the motorcycle be and the tension of the rope?

TvEAo.jpg


Homework Equations



guy: Ft = ma

weight: Ft - mg = ma

I think...

The Attempt at a Solution



I don't know how to get acceleration because I don't know Ft...
 
Last edited:
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  • #2
Does the question want you to calculate his accelerate on the ramp, or before it? Either way, you can't calculate tension right off the bat. The net force is going to equal the force of gravity on the 950kg mass. Divide that force by the system mass and you should get the acceleration before the ramp.
 
  • #3
fLambda said:
Does the question want you to calculate his accelerate on the ramp, or before it? Either way, you can't calculate tension right off the bat. The net force is going to equal the force of gravity on the 950kg mass. Divide that force by the system mass and you should get the acceleration before the ramp.

I'm not sure, it just asks for acceleration, I still need help with this question.
 
  • #4
Where does the 10 degrees come from? I don't see that in the question. If it's the slope of the ramp, that's not relevant. The question only asks you to consider circumstances before the ramp is reached, and nothing else is touching the ramp. The string is either horizontal or vertical.
The most obvious way to approach the question (not necessarily the most elegant) is to consider the weight and the motorcycle-with-rider as two separate systems but with certain parameters in common. Each has a set of forces and an acceleration. Which of these do they share? Can you write down the free body equation for each?
 
  • #5
haruspex said:
Where does the 10 degrees come from? I don't see that in the question. If it's the slope of the ramp, that's not relevant. The question only asks you to consider circumstances before the ramp is reached, and nothing else is touching the ramp. The string is either horizontal or vertical.
The most obvious way to approach the question (not necessarily the most elegant) is to consider the weight and the motorcycle-with-rider as two separate systems but with certain parameters in common. Each has a set of forces and an acceleration. Which of these do they share? Can you write down the free body equation for each?

Sorry! The 10 degrees came from a different question, I looked off the wrong question, I've fixed it now.
 
  • #6
PhysicsNoob76 said:
guy: Ft = ma
weight: Ft - mg = ma
Using the same m for both masses is going to be confusing. Use a different name for each different variable.
Also, make sure you're measuring accelerations all in the same direction.
 

Related to Calculating Acceleration and Tension in a Rope and Pulley System

What is the purpose of ropes and pulleys in dynamics?

Ropes and pulleys are used in dynamics to change the direction of a force. They allow for the transfer of force from one point to another, which can be useful in lifting or moving objects.

How do ropes and pulleys affect the mechanical advantage of a system?

Ropes and pulleys can increase the mechanical advantage of a system by reducing the amount of force needed to lift an object. This is because the weight of the object is distributed among multiple ropes and pulleys, reducing the overall force required.

Can ropes and pulleys be used to create a perpetual motion machine?

No, ropes and pulleys cannot be used to create a perpetual motion machine. This is because there will always be some friction and energy loss in the system, which will eventually cause the machine to stop moving.

What is the relationship between the number of pulleys and the mechanical advantage in a system?

The number of pulleys in a system is directly related to the mechanical advantage. The more pulleys there are, the greater the mechanical advantage will be, as the weight of the object will be distributed among multiple ropes and pulleys.

How do ropes and pulleys affect the work and energy involved in lifting an object?

Ropes and pulleys can decrease the amount of work and energy required to lift an object. This is because with a mechanical advantage, less force is needed to lift the object, and therefore less work and energy is required.

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