Maglev trains, like the one shown in the picture, use magnet fields to travel up to 600 miles per hour. Magnets on the bottom of the train and on the tops of the rails have similar magnetic poles. Based on properties of magnets, how do these magnets affect the train?A) The two magnetic fields repel each other, causing the train to levitate, or hover, above the rails.
B) The powerful magnets greatly reduce the force of gravity, resulting in less friction and greater speed.
C) The train is able to stop immediately because the magnets on the rails attract the magnets on the train.
D) Maglev trains have extremely powerful magnets, greatly decreasing the force of gravity and allowing them to float.

Scientists use laser range-finding to measure the distance to the moon with great accuracy. a brief laser pulse is fired at the moon, then the time interval is measured until the "echo" is seen by a telescope. a laser beam spreads out as it travels because it diffracts through a circular exit as it leaves the laser. in order for the reflected light to be bright enough to detect, the laser spot on the moon must be no more than 1.0 km in diameter. staying within this diameter is accomplished by using a special large-diameter laser. part a if λ = 540nm , what is the minimum diameter of the circular opening from which the laser beam emerges? the earth-moon distance is 384,000 km. express your answer to two significant figures and include the appropriate units.

What determines the amount of inertia an object has

Which pair of quantities includes one quantity that increases as the other decreases during simple harmonic motion?