1. A car is driving on a straight road. Depart at 9 am and arrive at the destination at noon 1 1: 30. It has traveled 200 kilometers. Can you calculate the speed of this car?

When the bus passes a station, the pointer of the passenger's watch just points to 9: 30, and when it passes the next station, it is 9: 32: 20. It is known that the distance between two stations is 2. 1 km. Find the speed.

3. The distance from Zhang Mingjia to school is 1500m, and the average speed of his bike ride is15km/h. How many hours does it take him to go to school by bike?

4. A train conductor with a length of150m passed through the tunnel at a constant speed of 36 kilometers per hour. The passenger on the train uses a stopwatch to measure that it takes him 12 seconds from entering the tunnel to leaving the tunnel. Find the length of the tunnel.

5. If a 200-meter-long train travels at a constant speed of 20 meters per second, how long will it take for the train to completely cross a bridge with a length of 1.8 kilometers?

6. A 200-meter-long train travels at a constant speed of 20 meters per second, and a tunnel with a length of 1.8 kilometers. How long does it take for the train to enter the tunnel completely?

7. The car moves for 20 minutes at a speed of 90km/h, and then moves for 10 minute at a speed of 72km/h, so as to find the average speed of the car in these 30 minutes.

8. If the echo reaches the human ear more than 0. 1 second later than the original sound, the human ear can separate the echo from the original sound.

(1) How far can sound travel in 0. 1 sec?

(2) How far does the wall reflect the echo from people? (The speed of sound is 340m/s)

9. The train must whistle before entering the tunnel. A train is heading for the tunnel at the speed of 126 km/h on a flat railway. The driver heard the whistle reflected from the cliff at the entrance of the tunnel 2 seconds later. If the speed of sound in the air is 340 m/s, how far is it from the tunnel entrance when the train whistles?

10. Blasting technology is often used in highway construction. In one blasting, a 96 cm long fuse was used to explode the explosives in the borehole, and the burning speed of the fuse was 0.8 cm/s.

After igniting the fuse, the igniter quickly runs away at an average speed of 5 meters per second, and calculates whether it can run to a safe zone 500 meters away from the explosion site before the explosion.

1 1. A train is traveling in a straight line at a constant speed of 20m/s. At this time, on the track parallel to it, a 300-meter-long truck is coming to the other side at a speed of10m/s. How many seconds does it take for a passenger sitting at the train window to see the truck passing by him?

12, A and B ran a 100-meter race. When A reaches the finish line, B still has a gap of 10 meter. If A is allowed to retreat from the starting line 10m and race with B at the same time, who will reach the finish line first? If B starts 10m ahead of the starting line and starts at the same time as A, who will reach the finish line first?

13. When the car is driving in a straight line, the speed in the first half is 20m/s and the speed in the second half is 30m/s.. What is the average speed of the whole journey?

14 My son rode his bicycle to the town for business at a speed of 5 meters per second. 10 minutes later, the father at home found that his son had forgotten his materials, so he drove to catch up with him at a speed of 20 meters per second and asked how long it would take to catch up with him.

15. For objects moving in a straight line at a uniform speed, their time ratio is 1: 4, and their distance ratio is 3: 1. What is their speed ratio?