Download presentation

1
Newton’s Laws June 5, 2012

3
Sample Problem 1 A tetherball leans against a smooth, frictionless post. The string is 1.4 m long and the ball has a radius of m with a mass of kg. What is the tension in the rope? What force does the pole exert on the ball?

4
Sample Problem 2 Two blocks are held in place on a frictionless incline. The mB = 10 kg and mA = 12 kg. The incline is tilted at an angle of 37o to the horizontal. Determine the tension in each rope.

5
Friction Friction is a resistive force. Kinetic friction is resistive to motion and static friction resists motion in the first place. In general, static friction is greater than kinetic friction

6
Kinetic Friction Will always point in a direction opposite to the direction of motion Ff = µkFn

7
Sample Problem 3 A box of mass 25 kg is pushed across a floor at a constant speed of 2 m/sec. What force is needed to push the box if there is a coefficient of friction of 0.2 between the box and the floor?

8
Sample Problem 4 The weight of the crate is 500 N and there is a coefficient of friction between the crate and the floor of If the worker pulls with a 400 N force, what is the acceleration of the crate?

9
Sample Problem 5 A pig slides down a chute inclined at 30o. If there is a coefficient of friction between pig and slide of 0.6, what is the acceleration of the pig down the slide?

10
**Static Friction Resists the desire of an object to move.**

Range of possibilities though we will typically look at the maximum case.

11
Static Friction

12
**Static Friction Harder to predict which way it will go. Ffs < µsFn**

Typical cases are the limits where Ffs = µsFn

13
Sample Problem 6 A person on a stationary 125 N box with a force of 75 N at 30o below the horizontal. Determine the coefficient of static friction if the box just starts to move.

14
Sample Problem 7 If the coefficient of static friction between the box and the truck bed is 0.6, what is the greatest acceleration the truck can have without the box slipping?

Similar presentations

OK

An 7.3-kg object rests on the floor of an elevator which is accelerating downward at a rate of 1.0 m/s 2. What is the magnitude of the force the object.

An 7.3-kg object rests on the floor of an elevator which is accelerating downward at a rate of 1.0 m/s 2. What is the magnitude of the force the object.

© 2019 SlidePlayer.com Inc.

All rights reserved.

To make this website work, we log user data and share it with processors. To use this website, you must agree to our Privacy Policy, including cookie policy.

Ads by Google