Q1: Calculate the speed of a car that travels 150 meters in 10 seconds. Express your answer in km/h.
Answer:
Speed = Distance / Time
Given:
Distance = 150 meters
Time = 10 seconds
Convert meters to kilometres and seconds to hours:
150 metres = 0.15 km
10 seconds = 10/3600 hours = 1/360 hours
Now calculate speed:
Speed = 0.15 km / (1/360 hour) = 0.15 × 360 = 54 km/h
Final answer: 54 km/h
Q2: A runner completes 400 meters in 50 seconds. Another runner completes the same distance in 45 seconds. Who has a greater speed and by how much?
Answer:
Speed = Distance / Time
Runner 1:
Distance = 400 metres
Time = 50 seconds
Speed = 400 / 50 = 8 m/s
Runner 2:
Distance = 400 metres
Time = 45 seconds
Speed = 400 / 45 ≈ 8.89 m/s
Conclusion:
Runner 2 is faster because he covers the same distance in less time.
Difference in speed = 8.89 m/s - 8 m/s = 0.89 m/s
Final answer: Runner 2 is faster by 0.89 m/s (approximately).
Q3: A train travels at a speed of 25 m/s and covers a distance of 360 km. How much time does it take?
Answer:
Time = Distance / Speed
Convert 360 km to metres:
360 km = 360,000 metres
Now calculate the time:
Time = 360,000 metres / 25 m/s = 14,400 seconds
Convert seconds to hours:
14,400 / 3600 = 4 hours
Final answer: 4 hours
Q4: A train travels 180 km in 3 hours. Find its speed in:
(i) km/h
(ii) m/s
(iii) What distance will it travel in 4 hours if it maintains the same speed throughout the journey?
Answer:
(i) Speed in km/h:
Speed = Distance / Time = 180 km / 3 hours = 60 km/h
(ii) Speed in m/s:
Convert 60 km/h to m/s:
60 km/h = (60 × 1000) / 3600 m/s = 60 × 5/18 m/s = 16.67 m/s (approx)
(iii) Distance in 4 hours:
Distance = Speed × Time = 60 km/h × 4 hours = 240 km
Final answers: (i) 60 km/h, (ii) 16.67 m/s (approx), (iii) 240 km
Q5: The fastest galloping horse can reach the speed of approximately 18 m/s. How does this compare to the speed of a train moving at 72 km/h?
Answer:
Convert the speed of the train to m/s:
72 km/h = (72 × 1000) / 3600 m/s = 72 × 5/18 m/s = 20 m/s
Comparison:
The horse moves at 18 m/s.
The train moves at 20 m/s.
Conclusion:
The train is faster than the galloping horse by:
20 m/s - 18 m/s = 2 m/s
Final answer: The train is faster by 2 m/s.
Q6: Distinguish between uniform and non-uniform motion using the example of a car moving on a straight highway with no traffic and a car moving in city traffic.
Answer: Uniform motion
When a car moves on a straight highway with no traffic, it travels with a constant speed. This is uniform motion, in which the distance covered in equal time intervals is the same.
Non-uniform motion
In city traffic, a car often slows down, stops, and speeds up again. This is non-uniform motion, where the distance covered in equal time intervals is not the same.
Q7: Data for an object covering distances in different intervals of time are given in the following table. If the object is in uniform motion, fill in the gaps in the table.
Therefore,
Q8: A car covers 60 km in the first hour, 70 km in the second hour, and 50 km in the third hour. Is the motion uniform? Justify your answer. Find the average speed of the car.
Answer:
Since the car covers different distances in each hour (60 km, 70 km and 50 km), the motion is non-uniform because equal time intervals do not have equal distances.
To find the average speed:
Total distance = 60 km + 70 km + 50 km = 180 km
Total time = 3 hours
Average speed = Total distance / Total time = 180 km / 3 hours = 60 km/h
Q9: Which type of motion is more common in daily life-uniform or non-uniform? Provide three examples from your experience to support your answer.
Answer:
Non-uniform motion is more common in daily life. Examples:
A car in city traffic: The car's speed changes because of traffic lights, junctions and other vehicles.
A bicycle in a park: The rider often slows while turning or to avoid obstacles, then speeds up again.
People walking: Walking speed varies because of obstacles, crowding or tiredness.
Q10: Data for the motion of an object are given in the following table. State whether the speed of the object is uniform or non-uniform. Find the average speed.
Since the distances covered in each equal time interval are not equal, the motion is non-uniform.
Average Speed = Total Distance / Total Time
Total distance = 60 m (final distance)
Total time = 100 s (final time)
Average speed = 60 m / 100 s = 0.6 m/s
Final answer: Motion is non-uniform; average speed = 0.6 m/s.
