Cambodia · Grade 9 · Practice Sheet 49

1. 1.

   A force of 71 N moves an object 31 m in the direction of the force. Find the work done.

   Formula:Work Done

   $W = F d$

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2. 2.

   A current of 2.5 A flows through a 15 Ω resistor. Find the voltage across it.

   Formula:Ohm's Law

   $V = I R$

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3. 3.

   A circle has a radius of 6 cm. Find its area. (Use π ≈ 3.14159)

   Formula:Area of a Circle

   $A = \pi r^2$

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4. 4.

   A device runs at 173 V drawing 1.6 A. Find its power consumption.

   Formula:Electrical Power

   $P = V I$

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5. 5.

   ៛ 3,600 is invested at 6% compound interest per annum for 2 years. Find the final amount (to 2 d.p.).

   Formula:Compound Interest

   $A = P\left(1 + \dfrac{r}{100}\right)^{t}$

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6. 6.

   A current of 1.1 A flows through a 13 Ω resistor. Find the voltage across it.

   Formula:Ohm's Law

   $V = I R$

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7. 7.

   Find the momentum of a 12 kg object moving at 27 m/s.

   Formula:Momentum

   $p = mv$

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8. 8.

   A value changes from 157 to 93. Find the percentage change (to 2 d.p.).

   Formula:Percentage Change

   $\%\,\text{change} = \dfrac{\text{new} - \text{old}}{\text{old}} \times 100$

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9. 9.

   A current of 0.8 A flows through a 24 Ω resistor. Find the voltage across it.

   Formula:Ohm's Law

   $V = I R$

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10. 10.

    A cone has base radius 4 cm and height 5 cm. Find its volume. (π ≈ 3.14159)

    Formula:Volume of a Cone

    $V = \tfrac{1}{3} \pi r^2 h$

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11. 11.

    A 9 kg object moves at 10 m/s. Find its kinetic energy.

    Formula:Kinetic Energy

    $KE = \tfrac{1}{2} m v^2$

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12. 12.

    Find the momentum of a 29 kg object moving at 11 m/s.

    Formula:Momentum

    $p = mv$

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13. 13.

    A wave has frequency 843 Hz and wavelength 2.89 m. Find its speed.

    Formula:Wave Speed

    $v = f\lambda$

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14. 14.

    Solve for x: 4x + 15 = 63.

    Formula:Solving a Linear Equation

    $x = \dfrac{c - b}{a}$

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15. 15.

    A value changes from 150 to 36. Find the percentage change (to 2 d.p.).

    Formula:Percentage Change

    $\%\,\text{change} = \dfrac{\text{new} - \text{old}}{\text{old}} \times 100$

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16. 16.

    ៛ 26 is shared in the ratio 1 : 1. Find each share.

    Formula:Dividing in a Ratio

    $\text{share} = \dfrac{\text{part}}{\text{total parts}} \times T$

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17. 17.

    ៛ 1,000 is invested at 3% simple interest per year for 3 years. Find the interest earned.

    Formula:Simple Interest

    $I = \dfrac{P \times r \times t}{100}$

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18. 18.

    A current of 2.7 A flows through a 30 Ω resistor. Find the voltage across it.

    Formula:Ohm's Law

    $V = I R$

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19. 19.

    A car travels 360 km in 4 hours. Find its average speed.

    Formula:Speed

    $v = \dfrac{d}{t}$

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20. 20.

    A wave has frequency 393 Hz and wavelength 1.44 m. Find its speed.

    Formula:Wave Speed

    $v = f\lambda$

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