Answer:
2.98 second
Explanation:
The severity index is defined by :
a is dimensionless constant that equals the number of multiples of g
Conditions are given as :
Initial velocity, u = 0
Acceleration, a = 34 m/s²
Final velocity, v = 16.4 km/h = 4.56 m/s
We can find t from the above data as follows :
As a is the acceleration that is multiple of g.
So,
So,
Severity index,
Hence, the severity index for the collision is 2.98 seconds.
Answer:(a)891.64 N
(b)0.7
Explanation:
Mass of crate
Crate slows down in
initial speed
inclination
From Work-Energy Principle
Work done by all the Forces is equal to change in Kinetic Energy
change in kinetic energy
(b)Coefficient of sliding friction
and
An example that illustrates the difference is the circular motion
Explanation:
Let's start by reminding the definition of the two quantities:
- Speed is a scalar quantity that tells "how fast" an object is moving, regardless of its direction of motion.
Speed can be calculate as:
where:
d is the distance travelled
t is the time taken
- Velocity is instead a vector quantity, given by:
where;
d is the displacement of the object (displacement is a a vector connecting the initial position to the final position of motion)
t is the time taken
Since it is a vector, velocity has both a magnitude and a direction, therefore it also takes into account the direction of motion of the object.
For an object in motion in a straight line, speed and velocity are the same. However, this is not always the case.
In fact, an example of motion in which the two quantities are different is the circular motion. Consider for example the object making one complete revolution along the circle. Therefore, its average speed is the ratio between the length of the perimeter (the distance) divided by the time taken:
where r is the radius of the circle.
However, the displacement of the object is zero (because the object returns to the starting point), and so the average velocity is also zero:
Learn more about speed and velocity:
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