Edexcel IAL M1 Moments Questions
Moment of a force; equilibrium of a rod under parallel coplanar forces, including non-uniform rods and rods on the point of tilting.
- M1 · Mechanics 1
- Calculator allowed
- 43 practice questions
What the questions test
The 43 M1 moments practice questions cover:
Worked example 1
A uniform plank of length $4\text{ m}$ and mass $18\text{ kg}$ rests horizontally on two supports at $A$ (left end) and $B$ ($3\text{ m}$ from $A$). A boy of mass $40\text{ kg}$ stands on the plank at a distance $x$ from $A$.
(a) Find, in terms of $x$, the reactions at $A$ and $B$. (5)
(b) State the maximum value of $x$ for which the plank does not tip. (2) Take $g = 9.8\text{ m s}^{-2}$.
Mark scheme
(a) Moments about $A$: $R_B \times 3 = 18g \times 2 + 40g \times x \Rightarrow R_B = \tfrac{(36 + 40x)g}{3}$ M1 A1. Total: $R_A + R_B = 58g \Rightarrow R_A = 58g - R_B = \tfrac{(174 - 36 - 40x)g}{3} = \tfrac{(138 - 40x)g}{3}$ M1 A1 A1.
(b) On point of tipping about $B$ when $R_A = 0$: $138 - 40x = 0 \Rightarrow x = 3.45$; but plank ends at $x = 4$, so max $x = 3.45\text{ m}$ M1 A1.
Worked example 2
A uniform beam $AB$ of length $8\text{ m}$ and mass $50\text{ kg}$ is supported horizontally by two vertical props at $C$ and $D$, where $AC = 1\text{ m}$ and $AD = 6\text{ m}$. A load $W_L$ is placed at $B$ so that the beam is on the point of tipping about $D$.
(a) Find $W_L$. (5)
(b) State the value of the reaction at $C$ in this critical case. (3) Take $g = 9.8\text{ m s}^{-2}$.
Mark scheme
(a) On point of tipping about $D$ ⇒ reaction at $C$ is zero B1. Take moments about $D$: weight of beam at midpoint (i.e. $4\text{ m}$ from $A$, so $2\text{ m}$ to the left of $D$) contributes clockwise moment $50g \times 2$; load $W_L$ at $B$ ($8\text{ m}$ from $A$, so $2\text{ m}$ to the right of $D$) contributes anticlockwise moment $W_L \times 2$ M1 M1 A1. Balance: $W_L \times 2 = 50g \times 2 \Rightarrow W_L = 50g = 490\text{ N}$; mass $= 50\text{ kg}$ A1.
(b) Reaction at $C$ = $0$ (definition of the tipping point) B1 B1 B1.
FAQ
What moments is in Edexcel IAL M1?
Moment of a force; equilibrium of a rod under parallel coplanar forces, including non-uniform rods and rods on the point of tilting.
Is M1 a calculator paper?
Yes, a calculator is allowed in M1, but method marks are only given for working you write down.
How are M1 moments questions marked?
With M marks for a correct method, A marks for accurate answers that depend on the M mark before them, and B marks for independent results, as in the worked examples on this page.