CHAPTER 12. FORCE,MOMENTUM AND IMPULSE 12.6
(d) The force that the escaping gases exerts on the rocket is greater thanthe weight
of the rocket.
- [IEB 2005/11 HG] Abox is held stationary ona smooth plane that is inclined at angle
θ to the horizontal.
N
F
θ w
F is the force exerted bya rope on the box. w is the weight of the boxand N is the
normal force of the plane on the box. Which ofthe following statementsis correct?
(a) tan θ =Fw
(b) tan θ =NF
(c) cos θ =Fw
(d) sin θ =Nw
- [SC 2001/11 HG1]As a result of three forces F 1 , F 2 and F 3 acting on it, an object at
point P is in equilibrium.
F 1 F 2
F 3
Which of the followingstatements is not true with reference to the three forces?
(a) The resultant of forces F 1 , F 2 and F 3 is zero.
(b) Forces F 1 , F 2 and F 3 lie in the same plane.
(c) Forces F 3 is the resultant of forces F 1 and F 2.
(d) The sum of the components of all the forcesin any chosen directionis zero.
- A block of mass Mis held stationary by a rope of negligible mass. The block rests on
a frictionless plane which is inclined at 30 ◦to the horizontal.
30 ◦
M
(a) Draw a labelled force diagram which showsall the forces acting on the block.
(b) Resolve the force due to gravity into components that are parallel and perpen-
dicular to the plane.
(c) Calculate the weightof the block when the force in the rope is 8N.
- [SC 2003/11] A heavy box, mass m, is lifted by means of arope R which passes over
a pulley fixed to a pole.A second rope S, tied torope R at point P, exertsa horizontal
force and pulls the boxto the right. After liftingthe box to a certain height, the box
is held stationary as shown in the sketch below.Ignore the masses of theropes. The
tension in rope R is 5 850 N.
