CAIE M2 2016 November — Question 4 8 marks

Exam BoardCAIE
ModuleM2 (Mechanics 2)
Year2016
SessionNovember
Marks8
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicProjectiles
TypeProjectile with bounce or impact
DifficultyStandard +0.3 This is a standard two-stage projectile problem with a bounce. Part (i) uses routine SUVAT equations to find time of flight and range. Part (ii) requires finding when speed equals 18 m/s using the speed formula √(u_x² + u_y²) across two flight phases, which is slightly more involved than basic projectile questions but still follows standard M2 techniques without requiring novel insight.
Spec3.02h Motion under gravity: vector form3.02i Projectile motion: constant acceleration model

4 A particle \(P\) is projected with speed \(20 \mathrm {~m} \mathrm {~s} ^ { - 1 }\) at an angle of \(30 ^ { \circ }\) above the horizontal from a point \(O\) on horizontal ground. \(P\) subsequently bounces when it first strikes the ground at the point \(A\).
  1. Find the time after projection when \(P\) first strikes the ground, and the distance \(O A\). When \(P\) bounces at \(A\) the horizontal component of the velocity of \(P\) is unchanged. The vertical component of velocity is \(8 \mathrm {~m} \mathrm {~s} ^ { - 1 }\) immediately after bouncing. \(P\) strikes the ground for the second time at \(B\) where it remains at rest.
  2. Calculate the first and last times after projection at which the speed of \(P\) is \(18 \mathrm {~m} \mathrm {~s} ^ { - 1 }\).

Question 4:
Part (i):
AnswerMarks Guidance
Working/AnswerMark Guidance
\(-20\sin 30 = 20\sin 30 - gT\)M1
\(T = 2\) sA1
\(OA = 34.6\) mB1
[3]
Part (ii):
AnswerMarks Guidance
Working/AnswerMark Guidance
\(V_v^2 = 18^2 - (20\cos 30)^2\)M1
\(V_V = (\pm)\ 4.899\)A1
\(4.899 = 20\sin 30 - gt\)M1
\(t = 0.51(0)\) sA1
\(-4.899 = 8 - gt\)
\(t = 1.29\)
\(T = 3.29\) sA1
[5]
## Question 4:

### Part (i):

| Working/Answer | Mark | Guidance |
|---|---|---|
| $-20\sin 30 = 20\sin 30 - gT$ | M1 | |
| $T = 2$ s | A1 | |
| $OA = 34.6$ m | B1 | |
| | [3] | |

### Part (ii):

| Working/Answer | Mark | Guidance |
|---|---|---|
| $V_v^2 = 18^2 - (20\cos 30)^2$ | M1 | |
| $V_V = (\pm)\ 4.899$ | A1 | |
| $4.899 = 20\sin 30 - gt$ | M1 | |
| $t = 0.51(0)$ s | A1 | |
| $-4.899 = 8 - gt$ | | |
| $t = 1.29$ | | |
| $T = 3.29$ s | A1 | |
| | [5] | |

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4 A particle $P$ is projected with speed $20 \mathrm {~m} \mathrm {~s} ^ { - 1 }$ at an angle of $30 ^ { \circ }$ above the horizontal from a point $O$ on horizontal ground. $P$ subsequently bounces when it first strikes the ground at the point $A$.\\
(i) Find the time after projection when $P$ first strikes the ground, and the distance $O A$.

When $P$ bounces at $A$ the horizontal component of the velocity of $P$ is unchanged. The vertical component of velocity is $8 \mathrm {~m} \mathrm {~s} ^ { - 1 }$ immediately after bouncing. $P$ strikes the ground for the second time at $B$ where it remains at rest.\\
(ii) Calculate the first and last times after projection at which the speed of $P$ is $18 \mathrm {~m} \mathrm {~s} ^ { - 1 }$.

\hfill \mbox{\textit{CAIE M2 2016 Q4 [8]}}