Quiz on lesson 1

1) If the uniform speed of a car equals 72 km/h this means that its speed equal .... m/s

• 20

• 25

• 18

• 40

Answer explanation

72 × 5/18 = 20 m/s

2) A car moving on a straight line covers a total distance ( d ) in a total time ( t ) the average speed of the car is given by the relation V = .......

• d÷t

• t÷d

• d×t

• d+t

3) A car moves in a certain direction by a speed equals ......km/h, its speed appears 50 km/h for an observer moves with a speed 30 km/h in the same direction of the car.

• 80

• 50

• 20

• 30

Answer explanation

real speed = relative speed + speed of the observer

= 50+30=80 km/h

4) When a moving objects takes double the time needed to cover half the distance so its speed ....

• decrease to half

• increase to double

• decrease to quarter

• remains constant

Answer explanation

V= d/t

= 0.5 / 2

= 1/4

5) The relative speed of a moving object relative to an observer move at the same speed in opposite direction is ......... its real speed.

• double

• half

• quarter

• the same as

6) A racer ends the race in 2 hours with average speed 25 km/h. if you know that the racer covers the first 15 km in an hour. calculate the speed of the racer after the first hour to complete the race in the given time?

• 15 km/h

• 20 km/h

• 5 km/h

• 35 km/h

Answer explanation

total distance = average speed × time

= 25 × 2 = 50 km

total time = 2 hours

he covered the first 15 km in 1 hour

so the remaining distance =

total distance - 15 = 50 -15 = 35 km

speed = d÷t = 35 ÷ 1= 35 km/h

7) A car moves at a regular speeds 90 km/h, this means that the cars covers a distance equals .... meters in 40 seconds.

• 25

• 4000

• 2000

• 1000

Answer explanation

speed = 90 × 5/18 = 25 m/s

d= speed × time

= 25 × 40 = 1000 m

8) If the speedometer of a moving car points to 90 km/h, therefore after two hours the car covers .....

• 90m

• 180m

• 90km

• 180km

Answer explanation

d= speed × time

= 90× 2 =180 km

9) A runner ran 1st 100 meters of a race in 8 seconds and the 2nd 100 meters in 12 seconds, therefore his average speed during the whole race is ...

• 8 m/s

• 10 m/s

• 20 m/s

• 10 km/s

Answer explanation

average speed = total distance ÷ total time

= (100+100) ÷(8+12) = 10 m/s

10) ..... equals the total distance covered by the moving body divided by the total time to cover this distance.

• speed

• average speed

• distance

• time