Physics
A submarine in the sea, sends ultrasonic ping and a stopwatch is started simultaneously. The stopwatch stops on receiving the reflected wave from an obstacle and reads 1 minute 40 seconds. Calculate the distance of the obstacle from the submarine (Speed of sound in water 1500 ms-1)
Related Questions
Richa weighing 40 kgf leaves point P on her skateboard and reaches point Q on the ground with velocity 10 ms-1. Calculate.
(a) the kinetic energy of Richa at point Q
(b) the vertical height of point P above the ground. (use g as 10 m/s2 and neglect friction)
(c) the kinetic energy of Richa at point R. (While moving from Q to R, she loses 500 J of energy against friction.)
Draw a block and tackle system of pulleys with velocity ratio equal to 3.
The diagrams given below show two sound boxes A and B with wires of same length (l) and tension (10 kgf) but different cross-sectional areas. Simultaneously, vibrating tuning forks of frequency 300 Hz are placed on the boxes A and B. The paper rider falls off in case of B but not in case of A.
(a) Name and explain the phenomenon responsible for the falling off of the paper rider in B.
(b) The wire A resonates with a tuning fork of frequency ‘f’. Is ‘f’ greater than, less than or equal to 300 Hz? Justify your answer.
The diagram shows wiring in a meter room of a building.
(a) What is the current rating of device X?
(b) What is the difference between the switch Z shown in the diagram and the switches you use to operate different appliances at home?
(c) What is the unit of the physical quantity displayed in Y?