4. Exercises

From Mechanics

(Difference between revisions)
Jump to: navigation, search
Current revision (17:36, 22 March 2010) (edit) (undo)
 
Line 40: Line 40:
<div class="ovning">
<div class="ovning">
a) Find the magnitude of the force
a) Find the magnitude of the force
-
6 <math>\mathbf{i}</math><math>+</math> 8
+
6 <math>\mathbf{i}</math><math>+</math>8
<math>\mathbf{j}</math> N, where <math>\mathbf{i}</math> and <math>\mathbf{j}</math> are
<math>\mathbf{j}</math> N, where <math>\mathbf{i}</math> and <math>\mathbf{j}</math> are
perpendicular unit vectors.
perpendicular unit vectors.
Line 53: Line 53:
===Exercise 4.4===
===Exercise 4.4===
<div class="ovning">
<div class="ovning">
-
A force is expressed as 9 <math>\mathbf{i}</math><math>+</math> 10
+
A force is expressed as 9 <math>\mathbf{i}</math><math>-</math>10
<math>\mathbf{j}</math> N.
<math>\mathbf{j}</math> N.

Current revision

       Theory          Exercises      


Exercise 4.1

The diagram shows a force and the unit vectors \displaystyle \mathbf{i} and \displaystyle \mathbf{j}

Image:E4.1.GIF

Express the force in terms of the unit vectors \displaystyle \mathbf{i} and \displaystyle \mathbf{j}


Exercise 4.2

Express each of the forces given below in the form \displaystyle a\mathbf{i}+b\mathbf{j}

Image:E4.2.GIF


Exercise 4.3

a) Find the magnitude of the force 6 \displaystyle \mathbf{i}\displaystyle +8 \displaystyle \mathbf{j} N, where \displaystyle \mathbf{i} and \displaystyle \mathbf{j} are perpendicular unit vectors.

b) Find the angle, to the nearest degree, between the force and the unit vector \displaystyle \mathbf{i}.



Exercise 4.4

A force is expressed as 9 \displaystyle \mathbf{i}\displaystyle -10 \displaystyle \mathbf{j} N.

a) Calculate the magnitude of this force.

b) Find the angle between the force and the unit vector \displaystyle \mathbf{i}.

Exercise 4.5

For each force given below find its magnitude and the angle between the force and the unit vector \displaystyle \mathbf{i}.

a) (\displaystyle 4\mathbf{i}+3\mathbf{j} ) N

b) (\displaystyle 4\mathbf{i}-3\mathbf{j} ) N

c) (\displaystyle -2\mathbf{i}+8\mathbf{j} ) N

d) (\displaystyle -5\mathbf{i}-7\mathbf{j} ) N



Exercise 4.6

The diagram shows two forces and the unit vectors \displaystyle \mathbf{i} and \displaystyle \mathbf{j}.

Image:E4.6.GIF

a) Express each force in the form \displaystyle a\mathbf{i}+b\mathbf{j}.

b) Find the magnitude of the resultant of these two forces.

c) Find the angle between the resultant force and the unit vector \displaystyle \mathbf{i}, and draw a diagram to show the direction of the resultant force.



Exercise 4.7

The diagram shows 3 forces and the perpendicular unit vectors \displaystyle \mathbf{i} and \displaystyle \mathbf{j}.

Image:E4.7.GIF

a) Express each force in terms of the unit vectors \displaystyle \mathbf{i} and \displaystyle \mathbf{j}.

b) Find the magnitude of the resultant of the 3 forces.



Exercise 4.8

A force \displaystyle {\mathbf{F}_{1}} = (\displaystyle 9\mathbf{i}+12\mathbf{j}) N and a second force \displaystyle {\mathbf{F}_{2}} = (\displaystyle -4\mathbf{i}+\mathbf{j}) N act on a particle.

(a) Find the magnitude of \displaystyle {\mathbf{F}_{1}}.


(b) Draw a diagram to show the direction of \displaystyle {\mathbf{F}_{1}}, and calculate the angle between \displaystyle {\mathbf{F}_{1}} and \displaystyle \mathbf{i}.


(c) Find the resultant of \displaystyle {\mathbf{F}_{1}} and \displaystyle {\mathbf{F}_{2}}.



Exercise 4.9

Four forces are shown on the diagram below.

Image:E4.9.GIF

a) Find the magnitude of the resultant of the four forces.

b) Find the angle between the resultant force and the unit vector \displaystyle \mathbf{i} correct to the nearest degree.