What is the tangential acceleration of a point

[RPDuece]

Help with Homework?


1. A circular disk of radius 30 cm is rotating with an angular acceleration of 1 radian/ s2. What is the tangential acceleration of a point on the rim of the disk? What is its centripetal acceleration if the angular speed is 3 rev / s?

2. A 980 Kg car traveling at 20 m/s rounds a curve of radius 40 m. What is the friction force that must act on the car to keep it in its circular path?

3. An object with a mass of 100 Kg is dragged up an incline by applying a force F. The total distance moved along the incline is 200 m and the vertical height gained in moving this distance is 20 m. What is the magnitude of the force F if friction is negligible? (Assume g = 10 m/s2)

4. What is the acceleration of an object that slides down an inclined plane that has a gradient of 1:4 (increases in height by 1 m when you travel along the plane 4 m) Ignore friction and assume g = 10 m/s2.

5. A force of 5 N is applied to a door perpendicular to its face at a distance of 0.75 m from its hinge. What is the torque on the door about the hinge?

6. The nut on a car wheel requires a torque of 75 N.m for opening it. A wrench 25 cm long is used to open the nut. What is the minimum force needed to open the nut?

 

[dextercioby]

Well,you haven't read the stickied threads,haven't you...?So do it.

Daniel.

 

[SphericalStrife]

yeah G, give it a good shot at this problem then we're here to help.

 

[UrbanXrisis]

I am doing these problems just out of curiosity and I'm having trouble remembering the equation for #3. Is the equation mgcos(theta) or mgsin(theta)? IT's really troubling me.

 

[Poncho]

What equation? If you mean the force of gravity opposite to F, it should simplify to mg if theta = 90, so it must be sin.

 

[dextercioby]

Is the velocity constant along the way...?If so,the the F should balance the tangential comonent of gravity perfectly.

Daniel.

 

[UrbanXrisis]

so F=mgsin(theta) where m=100kg, g=10m/s^2, theta=5.73

what if it asked for work? isn't that equation Fdcos(theta)?

 

[dextercioby]

Why...?There's no friction.Again,work must be done against gravity.It's the force you computed times the distance the object moves (200m).

Daniel.