Answer:
Because the sound travels faster in solids
Explanation:
Sound waves are mechanical waves, produced by the oscillations of the particles in a medium. The particles vibrate back and forth along the direction of propagation of the wave (longitudinal waves).
The speed of a sound wave depends on several factors, such as the density of the medium. In particular, the higher the density, the higher the speed of the wave, because in denser mediums the particles are more close to each other, so the transmission of the wave is more efficient since it can be transmitted better through the colliding particles.
For this reason, a sound wave travels faster in solids, and slower in gases.
Therefore in this problem, the sound of the oncoming train travels faster through the rail track (which consists of solids), rather than the air (which is a gas), so by putting the ear next to the track, it is possible to hear the sound of the train coming before the sound is heard in air.
Answer:
true
Explanation:
Friction occurs because no surface is perfectly smooth. Rougher surfaces have more friction between them. Heavier objects also have more friction because they press together with greater force. Friction produces heat because it causes the molecules on rubbing surfaces to move faster and have more energy.
When you’re driving on the freeway it’s necessary to keep your foot on the accelerator to keep the car moving at a constant speed. In this situation the net force on the car is zero.
The rate of change of the velocity of a particle with respect to time is called its acceleration. If the velocity of the particle changes at a constant rate, then this rate is called the constant acceleration.
Since we are using metres and seconds as our basic units, we will measure acceleration in metres per second per second. This will be abbreviated as m/s². It is also commonly abbreviated as ms⁻².
For example, if the velocity of a particle moving in a straight line changes uniformly (at a constant rate of change) from 2 m/s to 5 m/s over one second, then its constant acceleration is 3 m/s².
Zero acceleration means constant velocity. Also to be noticed is that the definition of acceleration does not involve any information about forces. Acceleration is a kinematic quantity. Irrespective of what forces are acting, if the velocity is constant, the acceleration is zero.
Learn more about acceleration here : brainly.com/question/605631
#SPJ4
Are silent run on power and have to be electricly charged
There are approximately 39 inches in 6 meters.<span />
