Question 1

Q1: An athlete completes one round of a circular track of diameter 200 m in 40 s . What will be the distance covered and the displacement at the end of 2...

Accepted Answer

Given: Diameter of circular track, $d = 200 	ext{ m}$ Radius of circular track, $r = \frac{d}{2} = \frac{200 	ext{ m}}{2} = 100 	ext{ m}$ Time taken for one round, $t = 40 	ext{ s}$ Total time, $T = 2 	ext{ minutes } 20 	ext{ seconds} = 2 	imes 60 	ext{ s} + 20 	ext{ s} = 140 	ext{ s}$  To...

Question 2

Q10: An artificial satellite is moving in a circular orbit of radius 42250 km . Calculate its speed if it takes 24 hours to revolve around the earth.

Accepted Answer

Given: Radius of the circular orbit, $r = 42250 	ext{ km} = 42250 	imes 10^3 	ext{ m} = 4.225 	imes 10^7 	ext{ m}$ Time taken for one revolution, $t = 24 	ext{ hours} = 24 	imes 60 	imes 60 	ext{ s} = 86400 	ext{ s}$ To Find: Speed of the satellite, $v$ Formula: Speed, $v = \frac{	ext{Dis...

Question 3

Q2: Joseph jogs from one end $A$ to the other end $B$ of a straight 300 m road in 2 minutes 30 seconds and then turns around and jogs 100 m back to point...

Accepted Answer

Given: Distance from A to B, $AB = 300 	ext{ m}$ Time taken from A to B, $t_{AB} = 2 	ext{ minutes } 30 	ext{ seconds} = 2 	imes 60 	ext{ s} + 30 	ext{ s} = 150 	ext{ s}$ Distance from B to C, $BC = 100 	ext{ m}$ Time taken from B to C, $t_{BC} = 1 	ext{ minute} = 60 	ext{ s}$ To Find: Ave...

Question 4

Q3: Abdul, while driving to school, computes the average speed for his trip to be $20 \mathrm{~km} \mathrm{~h}^{-1}$. On his return trip along the same ro...

Accepted Answer

Given: Average speed while driving to school, $v_1 = 20 	ext{ km/h}$ Average speed on the return trip, $v_2 = 30 	ext{ km/h}$ To Find: Average speed for Abdul's trip. Formula: Average speed $= \frac{	ext{Total distance travelled}}{	ext{Total time taken}}$ Let the distance to school be $x 	ext{...

Question 5

Q4: A motorboat starting from rest on a lake accelerates in a straight line at a constant rate of $3.0 \mathrm{~m} \mathrm{~s}^{-2}$ for 8.0 s . How far d...

Accepted Answer

Given: Initial velocity, $u = 0 	ext{ m/s}$ Acceleration, $a = 3.0 	ext{ m/s}^2$ Time, $t = 8.0 	ext{ s}$ To Find: Distance travelled, $s$ Formula: $s = ut + \frac{1}{2}at^2$ Calculation: $s = (0 	ext{ m/s})(8.0 	ext{ s}) + \frac{1}{2}(3.0 	ext{ m/s}^2)(8.0 	ext{ s})^2$ $s = 0 + \frac{1}{2} \...

Question 6

Q5: A driver of a car travelling at $52 \mathrm{~km} \mathrm{~h}^{-1}$ applies the brakes

Accepted Answer

The question is incomplete. It does not provide the full context. Therefore, I cannot provide a solution.

Question 7

Q6: Fig 7.10 shows the distance-time graph of three objects A,B and C . Study the graph and answer the following questions: (a) Which of the three is trav...

Accepted Answer

(a) Object B is travelling the fastest because its distance-time graph has the greatest slope. (b) No, all three are never at the same point on the road. Their lines do not intersect at a single common point. (c) According to the graph (Fig 7.10), when B passes A, C has travelled approximately 3.8 k...

Question 8

Q7: A ball is gently dropped from a height of 20 m . If its velocity increases uniformly at the rate of $10 \mathrm{~m} \mathrm{~s}^{-2}$, with what veloc...

Accepted Answer

Given: Initial velocity, $u = 0 	ext{ m/s}$ Distance, $s = 20 	ext{ m}$ Acceleration, $a = 10 	ext{ m/s}^2$ To Find: Final velocity, $v$, and time, $t$ Formula: $v^2 - u^2 = 2as$ $v = u + at$ Calculation: $v^2 - 0^2 = 2 	imes 10 	imes 20$ $v^2 = 400$ $v = \sqrt{400} = 20 	ext{ m/s}$ $20 = 0 +...

Question 9

Q8: The speed-time graph for a car is shown is Fig. 7.11. (a) Find how far does the car travel in the first 4 seconds. Shade the area on the graph that re...

Accepted Answer

(a) The distance travelled by the car in the first 4 seconds is equal to the area under the speed-time graph from t=0 to t=4s. Assuming the graph in Fig. 7.11 forms a triangle, the area of the triangle can be calculated as follows: Area = $\frac{1}{2} 	imes 	ext{base} 	imes 	ext{height} = \frac{...

Question 10

Q9: State which of the following situations are possible and give an example for each of these: (a) an object with a constant acceleration but with zero v...

Accepted Answer

(a) This situation is possible. An example is when an object is momentarily at rest at the highest point when thrown vertically upwards. At that instant, its velocity is zero, but it still has a constant acceleration due to gravity acting downwards. (b) This situation is not possible. If an object i...

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