OCR MEI Further Mechanics Major 2023 June — Question 3 5 marks

Exam BoardOCR MEI
ModuleFurther Mechanics Major (Further Mechanics Major)
Year2023
SessionJune
Marks5
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicCircular Motion 1
TypeConical pendulum – horizontal circle in free space (no surface)
DifficultyStandard +0.3 This is a standard conical pendulum problem requiring resolution of forces and application of circular motion principles. Part (a) involves simple vertical equilibrium (T cos θ = mg), while part (b) uses horizontal circular motion (T sin θ = mω²r). Both are routine applications of well-practiced techniques with straightforward algebra, making this slightly easier than average for Further Maths students who have covered circular motion.
Spec6.05c Horizontal circles: conical pendulum, banked tracks

\includegraphics{figure_3} The diagram shows a particle P, of mass 0.2 kg, which is attached by a light inextensible string of length 0.75 m to a fixed point O. Particle P moves with constant angular speed \(\omega \text{ rad s}^{-1}\) in a horizontal circle with centre vertically below O. The string is inclined at an angle \(\theta\) to the vertical. The greatest tension that the string can withstand without breaking is 15 N.
  1. Find the greatest possible value of \(\theta\), giving your answer to the nearest degree. [2]
  2. Determine the greatest possible value of \(\omega\). [3]

Question 3:
AnswerMarks Guidance
3(a) T c o s 0 .2 g  =
resolved. M0 if 0.2 used as the weight. Allow with
either T or 15
49
cos= =82
AnswerMarks Guidance
375A1 1.1
is the greatest value is required) allow awrt 82 and
awrt 1.44 (radians) - condone 8 2  but not < 82
Ignore incorrect use of inequality symbols if 82 given
as answer
[2]
AnswerMarks Guidance
(b)r 0 .7 5 s i n  = B1
T s i n 0 .2 ( 0 .7 5 s i n ) 2   =M1 3.3
and T resolved (allow with either T or 15). Allow
2 v
with r for radius and a r 2  = or a = but not just a
r
AnswerMarks Guidance
1 0  =A1 1.1
10.018… from using r = 0.74 and 8 2  = ) condone
1 0  but not 10
Ignore incorrect use of inequality symbols if 10 given
as answer
[3]
Question 3:
3 | (a) | T c o s 0 .2 g  = | M1 | 1.1 | Resolving vertically – correct number of terms and T
resolved. M0 if 0.2 used as the weight. Allow with
either T or 15
49
cos= =82
375 | A1 | 1.1 | For reference: 82.491881… (no indication of why this
is the greatest value is required) allow awrt 82 and
awrt 1.44 (radians) - condone 8 2  but not < 82
Ignore incorrect use of inequality symbols if 82 given
as answer
[2]
(b) | r 0 .7 5 s i n  = | B1 | 1.1 | Allow a value of 0.74 (or better) to imply this mark
T s i n 0 .2 ( 0 .7 5 s i n ) 2   = | M1 | 3.3 | Applying N2L horizontally – correct number of terms
and T resolved (allow with either T or 15). Allow
2 v
with r for radius and a r 2  = or a = but not just a
r
1 0  = | A1 | 1.1 | Condone awrt 10 from correct working (might see
10.018… from using r = 0.74 and 8 2  = ) condone
1 0  but not 10
Ignore incorrect use of inequality symbols if 10 given
as answer
[3]
\includegraphics{figure_3}

The diagram shows a particle P, of mass 0.2 kg, which is attached by a light inextensible string of length 0.75 m to a fixed point O.

Particle P moves with constant angular speed $\omega \text{ rad s}^{-1}$ in a horizontal circle with centre vertically below O. The string is inclined at an angle $\theta$ to the vertical.

The greatest tension that the string can withstand without breaking is 15 N.

\begin{enumerate}[label=(\alph*)]
\item Find the greatest possible value of $\theta$, giving your answer to the nearest degree. [2]
\item Determine the greatest possible value of $\omega$. [3]
\end{enumerate}

\hfill \mbox{\textit{OCR MEI Further Mechanics Major 2023 Q3 [5]}}