Advertisements
Advertisements
Question
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
Solution
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
RELATED QUESTIONS
What can you say about the motion of an object whose distance-time graph is a straight line parallel to the time axis?
Given figure shows the distance-time graph of three objects A, B and C. Study the graph and answer the following questions:
- Which of the three is travelling the fastest?
- Are all three ever at the same point on the road?
- How far has C travelled when B passes A?
- How far has B travelled by the time it passes C?
Figure shows the distance-time graph for the motion of two vehicles A and B. Which one of them is moving faster?
Figure: Distance-time graph for the motion of two cars
What can you say about the motion of a body whose distance-time graph is a straight line parallel to the time axis ?
Name the two quantities, the slope of whose graph give speed .
Four cars A, B, C and D are moving on a levelled, straight road. Their distance-time graphs are shown in the given figure. Which of the following is the correct statement regarding the motion of these cars?
A student draws a distance-time graph for a moving scooter and finds that a section of the graph is horizontal line parallel to the time axis. Which of the following conclusion is correct about this section of the graph?
Two friends leave Delhi for Chandigarh in their cars. A starts at 5 am and moves with a constant speed of 30 km/h, whereas B starts at 6 am and moves with a constant speed of 40 kmh-1. Plot the distance-time graph for their motion and find at what time the two friends will meet and at what distance from Delhi.
Write down the type of motion of a body in each of the following distance time-graph.
What are the uses of the graphical study of motion?
