78) A scooter of mass 120 kg is moving with a uniform velocity of 108 km per hour. The force required to stop the vehicle in 10 seconds is

79) Which is the example of 1st order lever?

80) Using a pulley block, a weight of 180 N is raised with a force 15 N. Then the mechanical advantage is

81) A screw jack has pitch of the screw p, length of lever l, then velocity ratio is given by

82) In which case the potential energy is decreases?