An 80 kg person is parachuting and is experiencing a downward acceleration of$\mathrm{2.8 }{\mathrm{m }\mathrm{s}}^{-2}$. The mass of the parachute is 5 kg. The upward force on the open parachute is (Take $g=\mathrm{9.8 }{\mathrm{m }\mathrm{s}}^{-2})$

A uniform rope of length $L$ and mass $M$ is placed on a smooth fixed wedge as shown. Both ends of rope are at same horizontal level. The rope is initially released from rest, then the magnitude of initial acceleration of rope is

A bob is hanging over a pulley inside a car through a string. The second end of the string is in the hand of a person standing in the car. The car is moving with constant acceleration $a$ directed horizontally as shown in figure. The other end of the string is pulled with constant acceleration $a$ (relative to car) vertically. The tension in the string is equal to,