Acceleration = (change in speed) / (time for the change).
Change in speed = (15 - 30) = -15 km/hr
Time for the change = 4 sec
Acceleration = (-15 km/hr) / (4 sec) = -3.75 km/hr per second .
Is that a lot ? Not much ?
Let's convert it to a unit that we can think about:
(-15 km/hr) x (1,000 m/km) x (1 hr / 3,600 sec) =
(-15 x 1,000) / (3,600) = -(4 and 1/6) m/sec .
So the acceleration of the bus is -(4 and 1/6) m/sec² .
The negative sign means that it slowed down.
(4 and 1/6) m/sec² is about 42% of the acceleration of gravity ...
the acceleration the bus would have if it drove off of a cliff.
When the car or the bus you're riding in slows down at that rate,
you feel 42% of your weight pulling you forward against your
seat belt. That's quite a drastic acceleration !
The normal force acting on the book by the inclined plane is most nearly 17N.
<h3>What is the normal force?</h3>
When a body is resting on the surface, the reaction force acting perpendicular to the surface of contact and in upward direction is equal to the the weight of the object.
On an inclined plane of 30 degree, a 2 kg block is resting. Its weight mg has two components, mgcos30 and mgsin30.
The Normal force will be equal to
N = mgcos30
N =2 x 9.81 x cos30
N = 17 Newtons
Thus, normal force acting on the book by the inclined plane is most nearly 17N.
Learn more about normal force.
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D- All wave lengths refract at the same angle
Explanation- The amount of refraction increases as the wavelength of light decreases. Shorter wavelengths of light are slowed more and consequently experience more bending than the longer wavelengths.
The area of the bar over r=4 is 0.468
