Block pulled at an angle with friction

In summary, a 4.62 kg block is pulled by a cord with a tension of 12.0 N and an angle of 33.0° above the horizontal. The coefficient of kinetic friction between the block and the floor is 0.100. The block starts moving at 3.10 s after being pulled and has a speed of 4.15 m/s.
  • #1
sentinel7e
3
0

Homework Statement



A 4.62 kg block located on a horizontal floor is pulled by a cord that exerts a force F = 12.0 N at an angle θ = 33.0° above the horizontal.

The coefficient of kinetic friction between the block and the floor is 0.100. What is the speed of the block 3.10 s after it starts moving?

Homework Equations



Fn = Uk * (m*g - F*sin[tex]\theta[/tex])

F = ma

The Attempt at a Solution



I solved for Fn and got Fn = 3.87. I assume I need to solve for acceleration and then get velocity but I am not sure.
 
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  • #2
sentinel7e said:

Homework Statement



A 4.62 kg block located on a horizontal floor is pulled by a cord that exerts a force F = 12.0 N at an angle θ = 33.0° above the horizontal.

The coefficient of kinetic friction between the block and the floor is 0.100. What is the speed of the block 3.10 s after it starts moving?

Homework Equations



Fn = Uk * (m*g - F*sin[tex]\theta[/tex])
You mean that's the friction force
F = ma

The Attempt at a Solution



I solved for Fn and got Fn = 3.87. I assume I need to solve for acceleration and then get velocity but I am not sure.
You correctly solved for the friction force, so yes, continue to solve for the acc. in the horiz direction.
 
  • #3
I'm still stuck, do I use F = ma to find accel and my F = 3.87? I tried it that way but got the wrong answer.
 
  • #4
sentinel7e said:
I'm still stuck, do I use F = ma to find accel and my F = 3.87? I tried it that way but got the wrong answer.
No, its F_net =ma. You have the friction force, 3.87 N, acting horizontally in one direction, and the horiz component of the cord tension force, F, pulling horizontally in the other direction. Calculate the horiz comp of the 12 N force, then solve for the net force and continue.
 
  • #5
Ok, I finally understood what you meant about if being friction force and not Fn. After applying the forces in both directions I was able to get the accel and ultimately the velocity of 4.15 m/s. Thanks for the help!
 

1. What is the difference between pulling a block at an angle with friction versus without friction?

When pulling a block at an angle without friction, the force applied will only cause the block to accelerate in the direction of the applied force. However, when friction is present, it will act in the opposite direction of the motion, making it more difficult to move the block and reducing the acceleration.

2. How does the coefficient of friction affect the block's motion when pulled at an angle?

The coefficient of friction is a measure of the resistance to motion between two surfaces in contact. When pulling a block at an angle, the coefficient of friction between the block and the surface it is on will determine how much force is needed to overcome the frictional force and move the block.

3. Can the angle at which the block is being pulled affect the amount of friction?

Yes, the angle at which the block is being pulled can affect the amount of friction. When the block is pulled at an angle, the normal force between the block and the surface is reduced, resulting in a decrease in the frictional force.

4. How does the weight of the block impact its motion when pulled at an angle with friction?

The weight of the block will play a role in determining the amount of friction present. A heavier block will have a greater normal force and thus a greater frictional force acting in the opposite direction of the motion. This will make it more difficult to move the block and decrease its acceleration.

5. Are there any strategies to reduce the effects of friction when pulling a block at an angle?

One strategy to reduce the effects of friction when pulling a block at an angle is to decrease the coefficient of friction between the block and the surface it is on. This can be done by using lubricants or by changing the surface material. Additionally, reducing the angle at which the block is being pulled can also decrease the frictional force. Another strategy is to increase the applied force, which can help overcome the frictional force and increase the acceleration of the block.

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