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Rearranging FormulaeEdexcel IGCSE Maths: Subtopic test

10 questions, 26 marks

Edexcel IGCSE Maths

Rearranging Formulae

Total 26 marks

Name

Class

Date

  1. 1
    A physics class studies motion formulae. The first is v=u+atv=u+at, where vv is final velocity, uu is initial velocity, aa is acceleration and tt is time. The second is s=12(u+v)ts=\frac{1}{2}(u+v)t. The third involves a pendulum's period, T=2πlgT=2\pi\sqrt{\frac{l}{g}}.
    (a)
    Make tt the subject of v=u+atv=u+at.
    [1 mark]
    • At=av−ut=\frac{a}{v-u}
    • Bt=v+uat=\frac{v+u}{a}
    • Ct=v−u−at=v-u-a
    • Dt=v−uat=\frac{v-u}{a}
    (b)
    Make uu the subject of s=12(u+v)ts=\frac{1}{2}(u+v)t.
    [1 mark]
    • Au=2st+vu=\frac{2s}{t}+v
    • Bu=2st−vu=\frac{2s}{t}-v
    • Cu=2s−vtu=2s-vt
    • Du=st−vu=\frac{s}{t}-v
    (c)
    Make ll the subject of T=2πlgT=2\pi\sqrt{\frac{l}{g}}.
    [1 mark]
    • Al=T24π2gl=\frac{T^2}{4\pi^2g}
    • Bl=4π2gT2l=\frac{4\pi^2g}{T^2}
    • Cl=gT24π2l=\frac{gT^2}{4\pi^2}
    • Dl=g(T2π)l=g\left(\frac{T}{2\pi}\right)

    Total for question 1: 3 marks

  2. 2
    A carpenter uses the perimeter formula P=2l+2wP=2l+2w for a rectangular frame, and later needs to convert temperatures using F=9C5+32F=\frac{9C}{5}+32.
    (a)
    The perimeter of a rectangle is given by P=2l+2wP=2l+2w, where ll is length and ww is width. Make ww the subject of the formula.
    [2 marks]
    (b)
    The formula F=9C5+32F=\frac{9C}{5}+32 converts a temperature CC in Celsius to FF in Fahrenheit. Make CC the subject of this formula.
    [2 marks]

    Total for question 2: 4 marks

  3. 3
    A quarry stores gravel in conical piles with volume V=13πr2hV=\frac{1}{3}\pi r^2h. The quarry also uses a formula for average speed over a journey, S=DTS=\frac{D}{T}, and needs it rearranged in terms of the travel time, TT, where the total distance is split into two legs.
    (a)
    The volume of a cone is given by V=13πr2hV=\frac{1}{3}\pi r^2h, where rr is the base radius and hh is the height. Make hh the subject of this formula, showing your working.
    [3 marks]
    (b)
    A delivery van's average speed is given by S=D1+D2T1+T2S=\frac{D_1+D_2}{T_1+T_2}, where D1,D2D_1,D_2 are two distances and T1,T2T_1,T_2 are two times. Make T2T_2 the subject of this formula.
    [3 marks]

    Total for question 3: 6 marks

  4. 4
    An engineer uses the kinetic energy formula E=12mv2E=\frac{1}{2}mv^2, where mm is mass in kilograms and vv is speed in metres per second. The same engineer also studies the formula for the surface area of a sphere, A=4πr2A=4\pi r^2, and a formula relating the period of oscillation of a spring, T=2πmkT=2\pi\sqrt{\frac{m}{k}}, where the subject mm needs to be made the subject after appearing under a square root.
    (a)
    An engineer uses the formula E=12mv2E=\frac{1}{2}mv^2 for kinetic energy, where mm is mass and vv is speed. Make vv the subject of the formula, showing every step and stating any restriction on the sign of your answer.
    [4 marks]
    (b)
    Make rr the subject of the surface area formula A=4πr2A=4\pi r^2, stating any restriction on the sign of your answer.
    [4 marks]
    (c)
    For a spring's oscillation period, T=2πmkT=2\pi\sqrt{\frac{m}{k}}, make mm the subject of the formula, showing every algebraic step clearly.
    [5 marks]

    Total for question 4: 13 marks

End of questions