Work? maybe just kinematic ( I don't even know what it is)

In summary, the conversation is about a physics problem involving a compressed spring, a frictionless track, and a physics student with a coefficient of kinetic friction on a 30 degree incline. The question is how to determine the student's speed just after losing contact with the spring and how far they travel up the incline. Despite some initial difficulties, the solution is eventually found using the equations of motion and kinematics.
  • #1
Kalie
46
0
Work?...maybe just kinematic...(please help! I don't even know what it is!)

The spring shown in the figure is compressed 50 cm and used to launch a 100 kg physics student. The track is frictionless until it starts up the incline. The student's coefficient of kinetic friction on the 30 degree incline is 0.15.

http://session.masteringphysics.com/problemAsset/1000852/6/knight_Figure_11_54.jpg

What is the student's speed just after losing contact with the spring?

How far up the incline does the student go?

The v_initial is incredibly easy to find, 14.1, but I can't seem to find how far he travels up the incline.
I've set it up a few different ways, and each time I get the wrong answer.

if Fx = -F_f - F_w*sinθ = ma
Fy = n - F_w*cosθ = 0 -> n = m*g*cosθ

then shouldn't -umgcosθ - mgsinθ = ma
giving you a = -g(ucosθ + sinθ) ?

and then the distance could be solved using the v_initial and a using kinematics?
But it is wrong? Could someone please explain?
 
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  • #2
never mind found it
 
  • #3



I can confirm that the initial speed can be easily found using the given information. However, finding the distance traveled up the incline is a bit more complex and requires a thorough understanding of kinematics and forces. It seems that you have correctly set up the equations for the forces acting on the student, but there may be a mistake in your calculations or a missing variable. I would recommend double checking your calculations and making sure all variables are accounted for. Additionally, it may be helpful to draw a free body diagram to visualize the forces acting on the student. If you are still having trouble, I suggest seeking assistance from a physics tutor or classmate. With the correct equations and variables, the distance traveled up the incline can be easily solved using kinematics. Keep in mind that the coefficient of kinetic friction may also play a role in the calculations. I hope this helps and good luck with your problem!
 

What is kinematics?

Kinematics is the branch of physics that studies the motion of objects without considering the forces that cause the motion.

How is kinematics used in work?

Kinematics is used to describe the motion of objects in work, such as the position, velocity, and acceleration of an object as it moves through a specific task or job.

What are the three main types of kinematic equations?

The three main types of kinematic equations are the equations for displacement, velocity, and acceleration. These equations describe the relationship between these variables in motion.

What is the difference between linear and rotational kinematics?

Linear kinematics deals with the motion of objects in a straight line, while rotational kinematics deals with the motion of objects around a fixed axis.

How does kinematics relate to other branches of physics?

Kinematics is closely related to other branches of physics, such as dynamics and mechanics, as it provides a foundation for understanding the motion of objects in the physical world.

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