A helicopter is trying to land on a submarine deck which is moving south at 17m/s. A balloon is moving at 12m/s with wind into the west. If to the submarine crew the helicopter is descending vetically at 5m/s, what is its speed? (a) relative to the water and (b) relative to the balloon. See fig.

A submarine that is not moving sends out a sonar sound wave travelling at 2000 m /s is, which reflects off a boat back to the submarine. The sonar crew detects the reflected wave 8 s after it was sent out. How far away is the boat from the submarine ?

A car moving at 35 m/s approaches a stationary whistle that emits a 220 Hz sound. The speed of sound is 343 m/s. What is the speed of the sound relative to the driver of the car?

A system is shown in the figure. Block A is moving with 1m//s towards left. Wedge is moving with 1m//s towards right. Then speed of the block B will be :

A plice siren emits a sound wave of frequency 440 Hz. The speed of sound is 332 m/s. if the siren is moving away from the listerner with a speed of 18 m/s relative to the air and the listerner is moving towards the siren with a speed of 68 m/s relative to the air, then what frequency does the listern hear?

A ship is sailing towards east in a traight line motion, with a speed of 10m//s . A man on the deck is moving across it , towards north, with a speed of 6 m//s calculate the velocity of the man relative to the sea.

A motor is fixed inside a box which is moving upwards with velocity 5 m//s . String is winding at the rate 3 m//s Then the velocity of block A will be.

A sailor in a boat, which is going due east with a speed of 8m//s observes that a submarine is heading towards north at a speed of 12m//s and sinking at a rate of 2 m//s .The commander of submarine observes a helicopter ascending at a rate of 5 m//s and heading towards west with 4 m//s .Find the speed of the helicopter with respect to boat.

A cart is moving horizontally along a straight line with constant speed 30 m/s. A projectile is to be fired from the moving cart in such a way that it will return to the cart after the cart has moved 120m. At what speed (relative to the cart, in m/s) must the projectile be fired ? (Take g=10m//s^2 )