The rebound coefficient between a tennis ball and a racket is defined as $g = v_2/ v_1$, where $v_1$ is the incoming speed of the ball and $v_2$ is the speed of the ball after rebound while the racket is at rest. A tennis ball falls from height $H$ to a racket at rest and bounces back to $0.8\ H. A$ tennis player is using the racket to hit an incoming tennis ball traveling at $150\ km/hr$ and the racket is moving at $100\ km/hr$. What is the speed of the ball after being hit? (Assume the mass of the racket >> that of the ball)..........$km/hr$
$323.6$
$223.6$
$150$
$250$
An airplane airspeed indicator reads $100 \,m / s$ and its compass shows that it is heading $37^{\circ}$ east of north. The meteorological information provided to the navigator is that the wind velocity is $20 \,m / s$ towards east. The speed of the airplane relative to the ground is closest to ............ $\,m / s$
Rain is falling vertically with a speed of $35 \;m s ^{-1} .$ Winds starts blowing after sometime with a speed of $12 \;m s ^{-1}$ in east to west direction. In which direction should a boy waiting at a bus stop hold his umbrella?
A bus appears to go with a speed of $25 \,km / hr$ to a car driver, driving at the rate $7 \,km / hr$ northwards. If the bus actually travels in east direction, its speed is ......... $km / h$
A man standing on a road hold his umbrella at $30^° $ with the vertical to keep the rain away. He throws the umbrella and starts running at $10\, km/hr$. He finds that raindrops are hitting his head vertically, the speed of raindrops w.r.t. the moving man, will be
To a person, going eastward in a car with a velocity of $25\, km/hr$, a train appears to move towards north with a velocity of $25\sqrt 3 $ $km/hr$. The actual velocity of the train will be..........$km/hr$