Answer:
1) 1.31 m/s2
2) 20.92 N
3) 8.53 m/s2
4) 1.76 m/s2
5) -8.53 m/s2
Explanation:
1) As the box does not slide, the acceleration of the box (relative to ground) is the same as acceleration of the truck, which goes from 0 to 17m/s in 13 s
2)According to Newton 2nd law, the static frictional force that acting on the box (so it goes along with the truck), is the product of its mass and acceleration
3) Let g = 9.81 m/s2. The maximum static friction that can hold the box is the product of its static coefficient and the normal force.
So the maximum acceleration on the block is
4)As the box slides, it is now subjected to kinetic friction, which is
So if the acceleration of the truck it at the point where the box starts to slide, the force that acting on it must be at 136.6 N too. So the horizontal net force would be 136.6 - 108.3 = 28.25N. And the acceleration is
28.25 / 16 = 1.76 m/s2
5) Same as number 3), the maximum deceleration the truck can have without the box sliding is -8.53 m/s2
Answer:
Yes both = and - g can be felt by a rider in a roller coaster.
Explanation:
It is crucial to understand how we feel gravity in this case.
We humans have no sensory organs to directly detect magnitude and direction like some birds and other creatures, but then how do we we feel gravity?
When we stand on our feet we feel our weight due to the normal reaction of floor on our feet trying to keep us stand and our weight trying to crush us down. In an elevator we feel difference in our weight (difference magnitudes of gravity) but actually we are feeling the differences in normal reactions under different accelerations of the elevator.
In the case of roller coaster you will feel +g as you sit on a chair in it, but will feel -g when you are in upside down position as roller coaster move.
When you are seated you will feel the normal reaction of seat on you giving you the feeling +g and the support of the buckles to stay in the roller coaster when you are upside down will give you the -g feeling.
<u>This is just the physics approach</u>, a biological approach can be given in association with sensors relating to ears.
The focal length of the eye-lens system will be exactly 2.0 cm. The lens thickness is altered depending on the distance of the object being viewed so that the focal length is ALWAYS equal to the lens-retina distance. If this is not true fr an individual, they need glasses :)
