OCR M1 2013 June — Question 5 10 marks

Exam BoardOCR
ModuleM1 (Mechanics 1)
Year2013
SessionJune
Marks10
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicConstant acceleration (SUVAT)
TypeSUVAT simultaneous equations: find u and a
DifficultyStandard +0.3 This is a straightforward SUVAT problem requiring systematic application of s=ut+½at² at two time points to form simultaneous equations, followed by standard mechanics calculations for angle (using g sin θ = 4) and mass (using R = mg cos θ). All steps are routine M1 techniques with no novel problem-solving required, making it slightly easier than average.
Spec3.02d Constant acceleration: SUVAT formulae3.02h Motion under gravity: vector form3.03f Weight: W=mg3.03i Normal reaction force

5 A particle \(P\) is projected with speed \(u \mathrm {~ms} ^ { - 1 }\) from the top of a smooth inclined plane of length \(2 d\) metres. After its projection \(P\) moves downwards along a line of greatest slope with acceleration \(4 \mathrm {~ms} ^ { - 2 }\). At the instant 3 s after projection \(P\) has moved half way down the plane. \(P\) reaches the foot of the plane 5 s after the instant of projection.
  1. Form two simultaneous equations in \(u\) and \(d\), and hence calculate the speed of projection of \(P\) and the length of the plane.
  2. Find the inclination of the plane to the horizontal.
  3. Given that the contact force exerted on \(P\) by the plane has magnitude 6 N , calculate the mass of \(P\).

Question 5(i):
AnswerMarks Guidance
Answer/WorkingMark Guidance
Single equation with one unknown from two equationsM1 Candidates using \(s\) or \(x\) instead of \(d\) can be given marks BoD
\(2d = 120\) leading to \(d = 60\)A0 From their SE
\(2d = 120\) with no further workA1
Question 5(ii):
AnswerMarks Guidance
Answer/WorkingMark Guidance
Value for mass assumed or wrongM1A0 Fortuitous
Question 5(iii):
AnswerMarks Guidance
Answer/WorkingMark Guidance
Candidates using cos in (ii) and sin in (iii)M1A0 Fortuitously correct mass
## Question 5(i):

| Answer/Working | Mark | Guidance |
|---|---|---|
| Single equation with one unknown from two equations | M1 | Candidates using $s$ or $x$ instead of $d$ can be given marks BoD |
| $2d = 120$ leading to $d = 60$ | A0 | From their SE |
| $2d = 120$ with no further work | A1 | |

## Question 5(ii):

| Answer/Working | Mark | Guidance |
|---|---|---|
| Value for mass assumed or wrong | M1A0 | Fortuitous |

## Question 5(iii):

| Answer/Working | Mark | Guidance |
|---|---|---|
| Candidates using cos in (ii) and sin in (iii) | M1A0 | Fortuitously correct mass |

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5 A particle $P$ is projected with speed $u \mathrm {~ms} ^ { - 1 }$ from the top of a smooth inclined plane of length $2 d$ metres. After its projection $P$ moves downwards along a line of greatest slope with acceleration $4 \mathrm {~ms} ^ { - 2 }$. At the instant 3 s after projection $P$ has moved half way down the plane. $P$ reaches the foot of the plane 5 s after the instant of projection.\\
(i) Form two simultaneous equations in $u$ and $d$, and hence calculate the speed of projection of $P$ and the length of the plane.\\
(ii) Find the inclination of the plane to the horizontal.\\
(iii) Given that the contact force exerted on $P$ by the plane has magnitude 6 N , calculate the mass of $P$.

\hfill \mbox{\textit{OCR M1 2013 Q5 [10]}}