Motion and Speed
Numericals
1. A car takes 20 minutes to cover a distance of 15 km. Calculate its speed in km/h and m/s.
2. The distance between two towns is 400 km. How much time would it take a car to cover this
distance at an average speed 50 km/h?
3. A man driving at an average speed of 40 km/h takes 6 hours to travel from one town to another.
What is the distance between the towns?
4. Plot a distance-time graph for a body travelling at a speed of 2.5 m/s.
5. The distance covered by a moving body over time is represented graphically in Figure 6.9. Find
its speed
Distance (m)
2
2 3
Time (s)
Answers
Answer:
1. A car takes 20 minutes to cover a distance of 15 km. Calculate its speed in km/h and m/s.
If the car travels 15km in 20 minutes, and 20 minutes are a third of an hour, so the speed per hour is : (15km * 3)/(20min * 3) = 45km/60min, as 60min is an hour so it's equal to 45km/h. Same way an hour has 3600 seconds so the speed for second is: (45km / 3600)/(1h / 3600) = 0.0125km/1s = 12.5m/s. I hope I could help.
2. The distance between two towns is 400 km. How much time would it take a car to cover this
Hence, the car will take 8 hours to cover this distance of 400 km with 50km /h speed. This can be explained as, Time taken by an object to cover a certain distance in given time is actually the ratio of total distance covered by its speed.Jul 25, 2018
3. A man driving at an average speed of 40 km/h takes 6 hours to travel from one town to another.
distances travelled is 80km for the next 20 km speed=40km/h for the next kilometer speed 20km
4. Plot a distance-time graph for a body travelling at a speed of 2.5 m/s.
If an object moves along a straight line, the distance travelled can be represented by a distance-time graph. In a distance-time graph, the gradient of the line is equal to the speed of the object. The greater the gradient (and the steeper the line) the faster the object is moving.
5. The distance covered by a moving body over time is represented graphically in Figure 6.9. Find
The attached figure shows a distance time graph. We know that the slope of distance time graph gives the speed of the body. From the attached figure,
Distance, d = 3 m
Time taken, t = 4 s
The total distance covered divided by total time taken is called speed of a body. It is given by :
v = 0.75 m/s
So, the speed of the body is 0.75 m/s. Hence, this is the required solution.