CHAPTER 12. FORCE,MOMENTUM AND IMPULSE 12.2
The question only asksfor horizontal forces. We will therefore not include the
force of the Earth on the trailer, or the force ofthe road on the trailer as these
forces are in a vertical direction.�F 1 : Force of car on trailer
(to the right) (2 000 N)Ff: Frictional force on trailer (to the left) (200 N)Step 3 : Determine the resultant force on the trailer.To find the resultant force we need to add all thehorizontal forces together.
We do not add verticalforces as the movementof the car and trailer will be in a
horizontal direction, and not up or down. FR= 2000 + (-200) = 1800 N to the
right.See simulation: VPkgj at http://www.everythingscience.co.za)Exercise 12 - 1
- A force acts on an object. Name three effectsthat the force can have on the object.
- Identify each of the following forces as contact or non-contact forces.
(a) The force between the north pole of a magnet and a paper clip.
(b) The force required toopen the door of a taxi.
(c) The force required tostop a soccer ball.
(d) The force causing aball, dropped from a height of 2 m, to fall to thefloor.- A book of mass 2 kgis lying on a table. Drawa labelled force diagramindicating all the forces
on the book. - A boy pushes a shopping trolley (mass 15 kg) with a constant force of 75 N. A constant frictional
force of 20 N is present.
(a) Draw a labelled force diagram to identify allthe forces acting on theshopping trolley.
(b) Draw a free body diagram of all the horizontal forces acting on the trolley.
(c) Determine the resultant force on the trolley.- A donkey (mass 250kg) is trying to pull a cart (mass 80 kg) with aforce of 400 N. The rope
between the donkey andthe cart makes an angleof 30◦with the cart. The cart does not move.
(a) Draw a free body diagram of all the forces acting on the donkey.
(b) Draw a force diagramof all the forces acting on the cart.
(c) Find the magnitudeand direction of the frictional force preventing the cart from moving.More practice video solutions or help at http://www.everythingscience.co.za(1.) 01vw (2.) 01vx (3.) 01vy (4.) 01vz (5.) 01w0