Question

(Date
17. The graph given alongside shows how the speed of a car changes with
time.
(i) What is the initial speed of the car?
(ii) What is the maximum speed attained by the car?
(iii) Which part of the graph shows zero acceleration?
(iv) Which part of the graph shows varying retardation?
(v) Find the distance travelled in first 8 hours..
Speed
10 FAP
8
10
0
2 4 6
Time (in hour)
​

Answer 1

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NOTE⤵⤵

Kindly Add pics of graph next time

SOLUTION ⤵⤵

A) The initial speed of the car is the speed at t=0. Hence, it is 10 km/ h.

b) The maximum speed is 35 km/hr. See the points B and C.

c) B to C shows zero acceleration as there is no change in speed of the car with respect to time.

d) The part from C to D shows varying retardation as its speed is not decreasing uniformly with the time. (You can see that in the part A to B we have uniform acceleration.)

e)To calculate the distance travelled in the first 8 hrs, you need to calculate the area below AB and BC, which is,

(35-10)×3/2 + 35× 5

37.5 + 175 = 212.5 km

You can also calculate this by applying the equations of motion.

Let me calculate the distance from A to B using the equations of motion.

u= 10

v=35

t= 3

a =( v-u)/t = (35-10)/3= 25/3

v²= u² +2as

s = (v² - u²)/ 2a

putting all the values we get, s= 67.5 km, which is equal yo the area of trapeziod formed below AB. That means I was correct previously and moderators wrongly marked my answer incorrect. hence, total distance = 67.5+175=242.5 km. The answer 212.5 km is incorrect and 242.5 km is the correct one.

Answer 2

hope it's helpful to you .