Forces

Question 1

What is tension?

Answer 1

A force that acts through taut (pulled tight) strings, cables, rods and springs. If the sting is slack (loose) then there is no tension. On a force diagram tension acts along the string pointing away from the object. Normal reaction force is perpendicular to the surface that the object is on.

Question 2

For a pulley problem, how do you work out the max height of one of the particles when the rope snaps after 1m?

Answer 2

Find the velocity when the particle snaps, (initial velocity is 0, you have distance and acceleration). use that final velocity as initial velocity and then make final velocity 0 at the top, with acceleration now in the opposite direction as it is falling. Once you find s, add all the distances together.

Question 3

Determine the distance that A travels from the instant that B hits the ground until A comes to instantaneous rest.

Answer 3

A will have the same velocity. The string is loose and therefore the tension is zero. V will also be zero as it’s the distance when A comes to rest.

Question 4

How would you use the modelling assumption that the tow-rope is inextensible for a car and trailer?

Answer 4

Trailer and car have the same acceleration.