(a)i) Define a torque. (ii)State three factors that determine a torque (b)(i) Define free fall. (ii) A body is thrown vertically upwards from the top of a tower 40.0m high with a velocity of 10.0ms\(^{-1}\). Calculate the time taken for the body to reach the ground. [g.= 10.0ms\(^{-2}\)] c) A cube of wood of side 8.0cm, floats at the interface between oil and water with 2.0cm of its surface below the interface as shown in the diagram below. Given that the relative densities of oil and water are 0.72 and 1.00 respectively, calculate the mass of the wood
Explanation
(a)i) Definition of a torque - The turning effect of force about an axis/pivot (ii) Factors that determine a torque - perpendicular distance of the force from the pivot - direction of the force. - magnitude of the force
(b)(i) Definition of free fall: - The vertical motion of a body only under the influence of gravity/its own weight (ii) Calculation of the time taken by a body thrown vertically upward to reach the ground S = 10t - \(\frac{1}{2}\)10t\(^2\) -40 = 10t - \(\frac{1}{2}\)10t\(^2\) x 10 t\(^2\) (t + 2)(t - 4) = 0 Time to fall to the ground, t = 4s (c) Calculation of the mass of wood: - Mass of wood = upthrust due to water displace + upthrust due to oil displaced = 1000 x 2 x 8 x 8 x 10 + 720 x 6 x 8 x 8 x 10 = 0.404kg
