Give an example where instantaneous speed is different from average speed
2 answers:
Answer:
Yes average speed may be different from instantaneous speed
Explanation:
When an object is moving with non uniform speed on a straight road or on a curved path then its instantaneous speed at different points of its path is different.
But if we will find the average speed of the path then it will be different from its actual average speed
For example we can say that let a Car is moving for speed 40 km/h for first hour of its journey and then for next hour of its journey its speed is 60 km/h
So here instantaneous speed of the car is either 40 km/h or 60 km/h
While to find the average speed we will say
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Answer:
A) 3.79 m/s B) 1.33 m
Explanation:
A)
- Horizontal movement:
- Once in the air, no forces act on the froghopper, so it keeps moving with the same initial horizontal speed.
- This horizontal component, is the projection of the velocity vector on the horizontal direction (x-axis):
- The horizontal displacement can be simply calculated as follows:
- Vertical movement:
- As the vertical and horizontal are independent each other (due to they are perpendicular, so there is no projection of one movement on the other), in the vertical direction, all happens as if would be a body thrown upward with a given initial vertical velocity.
- This velocity can be found as the projection of the velocity vector on the vertical direction (y-axis):
- Once in the air, the gravity will cause that the froghopper be slow down, till it reaches to the maximum height, where it will come momentarily to an stop.
- In that moment, we can apply the following kinematic equation:
- where vfy = 0, g = -9.8m/s2, hmax = 52.7 cm= 0.527 m
- Replacing by the givens, we can solve for voy:
- From the equation (1), we can solve for the magnitude of the initial velocity, v₀:
B)
- With the value of the magnitude of the initial velocity, we can find the horizontal component vox, as follows:
- In order to know the horizontal distance travelled, we need to find the time that the insect was in the air.
- We can use the equation for the vertical displacement, replacing this value by 0, as follows:
- Replacing by the givens, and rearranging terms, we can solve for t:
- Finally, we find the horizontal displacement, as follows:
- The horizontal distance covered by the froghopper was 1.33 m.
