Correct Answer: B. 2000N

Explanation

M.A = \(\frac{Eff \times V.r}{100} = \frac{80 \times 5}{100} = 4\)

Load = effort x M.A

= 4 x 500 = 2000N

Correct Answer: C. 358ms\(^{-1}\)

Explanation

- Travels a very long distance without losing its intensity

- Has a very narrow optical bandwidth.

- Gives more intense light/power

- Is monochromatic

Correct Answer: C. 10.80V

Explanation

(a) Specific heat capacity is the quantity of heat energy required to change the temperature of unit mass (1kg) of a substance by 1k.

(b) Diagram

Method Weigh empty calorimeter plus stirrer and record the mass M\(_1\), weigh empty calorimeter plus stirrer plus water and record the mass m. Weigh copper ball and record the mass Mc. Take the initial temperature of the water T\(_1\). Heat copper ball in water to temperature T and record T. Quickly transfer the copper ball into the calorimeter and stir. Take the final temperature of the mixture T\(_2\). Heat lost by copper ball = Heat gained by calorimeter; water and stirrer.

McCc (T - T\(_2\)) = (M\(_2\) - M\(_1\))C\(_w\)

(T\(_2\) - T\(_1\)) + M\(_1\) Cal(T\(_2\) - T\(_1\))

Were Cc, Cw and Cz = specific heat capacity of copper, water and calorimeter respectively.

Cc = \(\frac{ (M - M_1C + M Cal (T - T)}{Mc(T - T_2)}\)

Precautions:

(i) Calorimeter should be lagged.

(ii) Quickly transfer the hot ball to the calorimeter.

(iii) Shake off water from hot calorimeter metal ball before transfer.

(iv) Mix thoroughly the mixture with stirrer.

(c) Heat lost = 0.024 x 400 (230 - T).

Heat gained by water = 0.054 x 4200 (T - 31)

Heat gained by calorimeter = 0.060 x 400 (T - 31)

Heat lost = Heat gained = 0.024 x 400 (230 - T) = 0.054 x 4200

(T - 31) + 0.060 x 400 (T - 31) T = 38.34°C

Correct Answer: C. 300ms^-1

Explanation

F = ma

Therefore, a = \(\frac{F}{m}\)

a = \(\frac{7.5 \times 10^{3}}{0.025}\)

a = 3 x 10⁵m/s²

using V² = U² + 2ax;

V² = 0² + (2 x 3 x 10⁵ x 0.15)

Therefore V = 300 m/s

Correct Answer: A) 0.31 A

Correct Answer: C. concave mirror

Explanation

Concave mirrors are curved inwards and produce a magnified image of the object placed within its focus and pole. This is why dentists use concave mirrors to examine teeth, as it allows them to see the teeth in more detail.

Correct Answer: C. 72.8cm³

Correct Answer: D. evaporation