basic
☼ Some Important Concepts ( F + V = E + 2 ) :–
■ A cuboid has 8 vertices, 12 edges and 6 faces.
■ A tetrahedron has 4 vertices, 6 edges and 4 faces.
■ A Pyramid has 5 vertices, 8 edges and 5 fac…
(21) A train running at 40 kmph takes 18 seconds to pass a platform. Next, it takes 12 seconds to pass a man walking at the rate of 4 kmph in the same direction. Find the length of the train and that of the platform.
Soln. Let…
(16) A train 170 m long is running with a speed of 72 kmph. In what time will it pass a tunnel 230 m long ?
Soln. Speed of the train = u =
(11) An motor cars moves along the four sides of a square at the speeds of 20, 40, 60 and 80 km/hr. Find the average speed of the motor car around the field.
Soln. Since each side of the square be x km is same, average spee…
(6) A goods train leaves a station at a certain time at a fixed speed. After 10 hours, an express train leaves the same station and moves in the same direction at a uniform speed of 120 kmph. This train catches the goods train in 5 hours. F…