Advertisements
Advertisements
प्रश्न
A cyclist is travelling at 15 m s-1. She applies brakes so that she does not collide with a wall 18 m away. What deceleration must she have ?
Advertisements
उत्तर
We have to find the deceleration. We have the following information given,
Initial velocity, (u) = 15 m/s
Final velocity, (v) = 0 m/s
Distance travelled, (s) = 18 m
Let the acceleration be (a)
We can calculate acceleration by using the 3rd equation of motion,
`a = (v^2 - u^2)/(2s)`
Put the values in above equation to find the deceleration,
a = (0-225)/(36)
⇒ `a =-6.25 "m/s"^2`
Thus , the deceleration is 6.25 `"m/s"^2`
APPEARS IN
संबंधित प्रश्न
Show the shape of the distance-time graph for the motion in the following case:
A car parked on a side road.
What does the slope of a distance-time graph indicate ?
Fill in the following blank with suitable word :
The slope of a speed-time graph of a moving body gives its………………………..
The graph given alongside shows the positions of a body at different times. Calculate the speed of the body as it moves from :
(1) A to B,
(2) B to C, and
(3) C to D.
A spaceship is moving in space with a velocity of 60 kms−1. It fires its retro engines for 20 seconds and velocity is reduced to 55 kms−1. Calculate the distance travelled by a spaceship in 40 s, from the time of firing of the retro- rockets.
What are the uses of the graphical study of motion?
Complete the data of the table given below with the help of the distance-time graph given in the figure.
| Distance (m) | 0 | 4 | ? | 12 | ? | 20 |
| Time (s) | 0 | 2 | 4 | ? | 8 | 10 |
The area under velocity time graph represents ______.
Assertion: The position-time graph of a uniform motion in one dimension of a body can have a negative slope
Reason: When the speed of the body decreases with time then, the position-time graph of the moving body has a negative slope.
What do you infer if
- Distance – time graph is a straight line.
- The velocity-time graph is curved.
- Displacement time is zigzag.
