## Dynamics

Apologies:

I am not very tech savvy. Some minor issues with the quizes like ‘\hfill’ keeps appearing, not being able to put in lengthy explanations and some math terms not showing up properly. Please forgive me. Just ignore the ‘\hfill’, check the bottom of the page to see if there are any explanations for the questions which you are not sure of and refresh the page (press F5 on keyboard) if the math terms are not showing up properly. Thank you and have fun!

## Dynamics (O Level)

Congratulations - you have completed Dynamics (O Level). You scored %%SCORE%% out of %%TOTAL%%. Your performance has been rated as %%RATING%%
 Question 1
A force of 8N is exerted on a block of 4kg. What is the acceleration of the block?
 A $2m{s^{ - 2}}$ B $4m{s^{ - 2}}$ C $6m{s^{ - 2}}$ D $8m{s^{ - 2}}$
Question 1 Explanation:
\begin{gathered} F = ma \hfill \\ 8 = 4a \hfill \\ a = 2 \hfill \\ \end{gathered}
 Question 2
A block of 4kg is being pushed by a force, causing it to accelerate at $6m{s^{^{ - 2}}}$. What is the magnitude of this force?
 A 0.67 N B 1.5 N C 2 N D 24 N
Question 2 Explanation:
\begin{gathered} F = ma \hfill \\ F = (4)(6) \hfill \\ a = 24 \hfill \\ \end{gathered}
 Question 3
A block of 4 kg is being pushed by a force of 8 N, and experiences a frictional force of 6 N. What is the acceleration of the block?
 A $0.5m{s^{ - 2}}$ B $0.67m{s^{ - 2}}$ C $1.5m{s^{ - 2}}$ D $2m{s^{ - 2}}$
Question 3 Explanation:
Resultant force on block: $8N - 6N = 2N$ Hence, \begin{gathered} F = ma \hfill \\ 2 = 4a \hfill \\ a = 0.5 \hfill \\ \end{gathered}
 Question 4
A block of 4 kg is being pushed by a force of 8 N rightwards and another force of 3 N leftwards. It also experiences a frictional force of 2 N. What is the acceleration of the block?
 A $0.5m{s^{ - 2}}$ B $0.75m{s^{ - 2}}$ C $1.75m{s^{ - 2}}$ D $3m{s^{ - 2}}$
Question 4 Explanation:
Resultant force on block: $8N - 3N - 2N = 3N$ Hence, \begin{gathered} F = ma \hfill \\ 3 = 4a \hfill \\ a = 0.75 \hfill \\ \end{gathered}
 Question 5
A block of 4 kg is being pushed by a force of 8 N rightwards and another force of 3 N leftwards. It also experiences a frictional force of 5 N. What is the acceleration of the block?
 A $0m{s^{ - 2}}$ B $0.75m{s^{ - 2}}$ C $2m{s^{ - 2}}$ D $2.5m{s^{ - 2}}$
Question 5 Explanation:
Resultant force on block: $8N - 3N - 5N = 0N$ \begin{gathered} F = ma \hfill \\ 0 = 4a \hfill \\ a = 0 \hfill \\ \end{gathered}
 Question 6
A ball is moving at a constant speed of $3m{s^{ - 1}}$. 2 forces of 8 N then start acting on it from directly opposite directions. Which of the following is correct?
 A The ball will stop immediately B The ball will slow to a stop C The ball will continue at its original speed D The ball will increase in speed
Question 6 Explanation:
Since there is no resultant force acting on the ball, its state of motion will not be changed as well.
 Question 7
2 blocks of 6 kg and 2 kg are pulled by a force of 8 N as shown. What is the acceleration of block B?
 A $1m{s^{ - 2}}$ B $1.33m{s^{ - 2}}$ C $3m{s^{ - 2}}$ D $4m{s^{ - 2}}$
Question 7 Explanation:
Since block B is attached to block A, both blocks will accelerate at the same rate due to the 8 N force. Acceleration of block A and B is: \begin{gathered} F = ma \hfill \\ 8 = (6 + 2)a \hfill \\ a = 1 \hfill \\ \end{gathered}
 Question 8
2 blocks of 6 kg and 2 kg are pulled by a force of 8 N as shown. What is the tension in the string between block A and block B?
 A 2 NHint: 6 B 4 N C 6 N D 8 N
Question 8 Explanation:
Since block B is attached to block A, both blocks will accelerate at the same rate due to the 8 N force. Acceleration of block A and B is: \begin{gathered} F = ma \hfill \\ 8 = (6 + 2)a \hfill \\ a = 1 \hfill \\ \end{gathered} Since the tension on the string is the force causing block A's acceleration, \begin{gathered} F = ma \hfill \\ F = (6)(1) \hfill \\ F = 6 \hfill \\ \end{gathered}
 Question 9
2 identical blocks are pulled by a force of 8 N as shown. A frictional force of 2 N acts on each of the blocks. What is the tension in the string between block A and block B?
 A 2 N B 4 N C 6 N D 8 N
 Question 10
2 blocks of 6 kg and 2 kg are pulled by a force of 8 N as shown. A frictional force of 2 N acts on each of the blocks. What is the tension in the string between block A and block B?
 A 3 N B 4 N C 5 N D 6 N
Question 10 Explanation:
Resultant force: $8 - 2 - 2 = 4$ Resultant force on block A: $4 \times \frac{6}{{6 + 2}} = 3$ Tension in string: $3 + 2 = 5$
 Question 11
A block of 3 kg is pulling another block of 5 kg via a pulley as shown below. Assuming there is no friction, what is the acceleration of the 3 kg block? ($g = 10m{s^{ - 2}}$)
 A $1.67m{s^{ - 2}}$ B $3.75m{s^{ - 2}}$ C $8m{s^{ - 2}}$ D $10m{s^{ - 2}}$
Question 11 Explanation:
Force exerted by the 3 kg block: $\begin{gathered} F = ma \hfill \\ F = (3)(10) \hfill \\ F = 10 \hfill \\ \end{gathered}$ Both the blocks accelerate uniformly. Acceleration of both the blocks: $\begin{gathered} F = ma \hfill \\ 30 = (5 + 3)a \hfill \\ a = 3.75 \hfill \\ \end{gathered}$
 Question 12
A block of 3 kg is pulling another block of 5 kg via a pulley as shown below. Assuming there is no friction beside a frictional force of 10 N acting on the 5 kg block, what is the acceleration of the 3 kg block? ($g = 10m{s^{ - 2}}$)
 A $2.5m{s^{ - 2}}$ B $3.33m{s^{ - 2}}$ C $5m{s^{ - 2}}$ D $10m{s^{ - 2}}$
Question 12 Explanation:
Force exerted by the 3 kg block: $\begin{gathered} F = ma \hfill \\ F = (3)(10) \hfill \\ F = 10 \hfill \\ \end{gathered}$ Resultant force on the 2 blocks: $30 - 10 = 20$ Both the blocks accelerate uniformly. Acceleration of both the blocks: $\begin{gathered} F = ma \hfill \\ 20 = (5 + 3)a \hfill \\ a = 2.5 \hfill \\ \end{gathered}$
 Question 13
A particle experiences 2 forces as shown below. What is the resultant force on the particle?
 A 5N, ${36.9^o}$ East of South B 5N, ${36.9^o}$ West of South C 7N, ${36.9^o}$ East of South D 7N, ${36.9^o}$ West of South
Question 13 Explanation:
Magnitude of resultant force: $\begin{gathered} {F^2} = {4^2} + {3^3} \hfill \\ F = 5 \hfill \\ \end{gathered}$ Southwards + Westwards = Southwest direction Angle: $\begin{gathered} \tan \theta = \frac{3}{4} \hfill \\ \theta = {36.9^o} \hfill \\ \end{gathered}$ Direction is ${36.9^o}$ West of South
 Question 14
A particle experiences 3 forces as shown below. What is the magnitude of the resultant force on the particle?
 A 2.1 B 2.6 C 3.2 D 4.8
Once you are finished, click the button below. Any items you have not completed will be marked incorrect.
There are 14 questions to complete.

## More Explainations

### Qn 13

Horizontal component of diagonal force:
$\begin{gathered} \cos {30^o} = \frac{{{F_h}}}{3} \hfill \\ {F_h} = 2.60 \hfill \\ \end{gathered}$

Vertical component of diagonal force:
$\begin{gathered} \sin {30^o} = \frac{{{F_v}}}{3} \hfill \\ {F_v} = 1.5 \hfill \\ \end{gathered}$

Resultant horizontal force:
$4 - 2.6 = 1.4$
Resultant vertical force:
$3 - 1.5 = 1.5$
Resultant force:
$\begin{gathered} {F_r}^2 = {(1.4)^2} + {(1.5)^2} \hfill \\ {F_r} = 2.05 \approx 2.1 \hfill \\ \end{gathered}$

Home Home Dynamics
© Free Physics Questions