Question
A was travelling from point X to point Y. He increased
his speed by 10 km/h after every hour. He reached his destination in 20 hours. If his initial speed was 25 km/h, then what was his average speed in the whole journey?Solution
Total distance travelled by A = (20/2) × {2 × 25 + (20 – 1) × 10} = 10 × (50 + 190) = 2400 km Required average speed = 2400/20 = 120 km/h
Ultrasonic waves, propagating through a medium, can be detected by:
Global warming is expected to result in
Which mirror always forms virtual, erect, and diminished image?
A wire loop in the shape of a square of side a carries a current I. If an infinitely long straight wire carrying the same current passes through the cen...
Which law states that the current through a conductor is directly proportional to the voltage across it?
Which of the following does not affect the value of acceleration due to gravity?
A plane electromagnetic wave travels in vacuum along z-direction. What can you say about the directions of its electric and magnetic field vectors? If t...
What is the point called where the total mass of a body is considered to be concentrated?
Match the following machines with their working principles:
(i) Electric motor - (a) Heat energy into mechanical energy
(ii) Steam engin...
A body is projected vertically upwards with a velocity of 98 m/s. The time interval during which it is at a height greater than 392 m is:
(Take g...
Relevant for Exams:
