Who is faster?

The idea

The distances moved by objects in a given interval of time decide which is faster: the one that covers more distance in the same time is faster and has a higher speed.

A race

Prerna and her friends run a race on a straight track. They all start together. After some time they are no longer side by side.

How can we tell who is running faster?

• The one who has covered more distance in the same time
• The one with the loudest shoes
• The one who started last

Slide the clock

Slide the clock up to 10 s. Compare how far each runner has gone.

Same time, compare distances

At the same time, Prerna was farthest from the start. She covered the most distance, so she is the fastest. Tara covered the least. (The numbers in the race are examples.)

The distances moved by objects in a given interval of time decide which is faster: the one that covers more distance in the same time is faster and has a higher speed.

Notes

The distances moved by objects in a given interval of time decide which is faster: the one that covers more distance in the same time is faster and has a higher speed.

Check yourself

Two runners run for the same time. Runner P covers 60 m. Runner Q covers 50 m. Who is faster?

Who has the higher speed?

Four trains travel for 1 h. Which one is the fastest?

In a race all runners must be compared …

• Q. Q covered less distance in the same time, so Q is slower.
• P — correct. Yes!
• Both are equally fast. They covered different distances in the same time, so one is faster.
• The one who runs for a longer time. Time is kept the same when we compare. What decides is the distance covered.
• The one who stops first. Stopping first does not decide it. The distance covered in the same time does.
• The one who covers more distance in the same time — correct. Yes!
• The one that covered the greatest distance — correct. Yes!
• The one that covered the least distance. That is the slowest of them.
• The one that is the longest. The length of a train does not decide its speed.
• at different times. Comparing at different times would not be fair. Use the same time.
• at the same time — correct. Yes!
• after they have all stopped for a rest. Compare how far each has gone in the same time.