Download Quiz 7

Quiz 7
Multiple-choice questions on forces acting at a point
1. A physical quantity which has direction as well as magnitude is known as a:
(a) force (b) vector (c) scalar (d) weight
2.
Which of the following is not a scalar quantity?
(a) velocity (b) potential energy
(c) work
(d) kinetic energy
3.
Which of the following is not a vector quantity?
(a) displacement (b) density
(c) velocity
(d) acceleration
4.
5.
6.
7.
Which of the following statements is false?
(a)
Scalar quantities have size or magnitude only
(b)
Vector quantities have both magnitude and direction
(c)
Mass, length and time are all scalar quantities
(d)
Distance, velocity and acceleration are all vector quantities
If the centre of gravity of an object which is slightly disturbed is raised and the object returns to its original
position when the disturbing force is removed, the object is said to be in
(a)
neutral equilibrium
(b)
stable equilibrium
(c)
static equilibrium
(d)
unstable equilibrium
Which of the following statements is false?
(a)
The centre of gravity of a lamina is at its point of balance
(b)
The centre of gravity of a circular lamina is at its centre
(c)
The centre of gravity of a rectangular lamina is at the point of intersection of its two sides
(d)
The centre of gravity of a thin uniform rod is halfway along the rod
The magnitude of the resultant of the vectors shown in Figure 19.29 is:
(a) 2 N (b) 12 N (c) 35 N (d) −2 N
5N
7N
Figure 19.29
Science for Engineering. 978-1-138-82688-5, © John Bird. Published by Taylor & Francis. All rights reserved.
8.
The magnitude of the resultant of the vectors shown in Figure 19.30 is:
(a) 7 N (b) 5 N (c) 1 N (d) 12 N
4N
3N
Figure 19.30
9.
10.
11.
Which of the following statements is false ?
(a)
There is always a resultant vector required to close a vector diagram representing a system of coplanar
forces acting at a point, which are not in equilibrium
(b)
A vector quantity has both magnitude and direction
(c)
A vector diagram representing a system of coplanar forces acting at a point when in equilibrium does
not close
(d)
Concurrent forces are those which act at the same time at the same point
Which of the following statements is false?
(a)
The resultant of coplanar forces of 1 N, 2 N and 3 N acting at a point can be 4 N
(b)
The resultant of forces of 6 N and 3 N acting in the same line of action but opposite in sense is 3 N
(c)
The resultant of forces of 6 N and 3 N acting in the same sense and having the same line of action is
9N
(d)
The resultant of coplanar forces of 4 N at 0◦ , 3 N at 90◦ and 8 N at 180◦ is 15 N
A space diagram of a force system is shown in Figure 19.31. Which of the vector diagrams in Figure 19.32
does not represent this force system?
10 N
30 N
20 N
Figure 19.31
12.
With reference to Figure 19.33, which of the following statements is false?
(a)
The horizontal component of FA is 8.66 N
(b)
The vertical component of FB is 10 N
(c)
The horizontal component of FC is 0
(d)
The vertical component of FD is 4 N
13.
The resultant of two forces of 3 N and 4 N can never be equal to:
(a) 2.5 N (b) 4.5 N (c) 6.5 N (d) 7.5 N
The magnitude of the resultant of the vectors shown in Figure 19.34 is:
(a) 5 N (b) 13 N (c) 1 N (d) 63 N
10 N
R
= 1 esu
7. ltan
32 t
N
30 N
30 N
10 N
10 N
R
= 1 esu
7.3 ltan
2N t
20 N
10 N
20 N
20 N
30 N
(c)
(b)
(a)
Scale
0
10
20
nt
ta
ul 2 N
es 3
R 17.
=
R
= esu
17 lta
.3 nt
2
N
30 N
20 N
(d)
30 N
Figure 19.32
FB = 20 N
FA = 10 N
150°
30°
60°
FC = 5 N
FD = 8 N
Figure 19.33
3N
3N
7N
Figure 19.34
1. (b) 2. (a) 3. (b) 4. (d) 5. (b) 6. (c) 7. (b)
8. (b) 9. (c) 10. (d) 11. (c) 12. (d) 13. (d) 14. (a)
Answers
14.