1 ) Two masses of 4 0 k g and 3 0 k g are connected by a weightless string passing over a friction less pulley as shown in the figure. The acceleration of the system would be: Gravitation force on A, F A = m g sin 3 0 = 4 0 × 1 0 × 0 . 5 = 2 0 0 N Gravitation force on B, F B = M g sin 3 0 = 3 0 × 1 0 × 0 . 5 = 1 5 0 N F n e t = F A − F B ⇒ ( M + m ) a = F A − F B ⇒ a = M + m F A − F B = 4 0 + 3 0 2 0 0 − 1 5 0 = 0 . 7 1 m s − 2 Hence, acceleration of the system is 0 . 7 1 m s − 2 Acceleration of the particle when its velocity becomes half of the initial velocity. V = − ( 5 0 2 0 ) x V = 5 − 2 x a = d t d v = 5 − 2 d t d x = 5 − 2 V a = 5 − 2 V initial velocity ( u ) = 2 0 m / s 2 u = 1 0 m / s a = 5 − 2 ( 1 0 ) = − 4 m / s 2 . A model airplane with mass 0 . 7 5 0 k g is tethered to the ground by a wire so that it flies in a horizontal circle ...