Question

1.Which expression calculates the speed in meters per second of an object that travels a distance of 40 m every 10 s?

10 ÷ 40​​
40 + 10​​
40 ÷​ 10​
40⋅10 ​

2.How long would it take to travel 425 m at the rate of 50 m/s ?

8.5 s
375 s
475 s
21,250 s

3.A boat travels for 4 hours at a constant speed of 35.25 km/h.

How far does the boat travel?

105 km
120 km
141 km
352 km

4.Anton's family drove 216 mi to the lake averaging 48 ​ mi/h ​ . On the return trip home they averaged 54 mi/h .

What was the total time that Anton's family spent driving to and from the lake?

8.0 h
8.5 h
9.0 h
9.5 h

5.A train traveled 210 mi in 3.5 h to its first stop. It then continued on traveling another 130 mi in 2.5 h.

What was the average speed of the train for the entire journey?

Round to the nearest tenth, if necessary.

52.0 mi/h
56.0 ​ mi/h ​
56.7 ​ mi/h ​
60.0 ​ mi/h ​

Answer 1

Explanation:

The key for this assignment is look at the units and values given. What is the desired units/value? You could also use d = r*t assuming a constant rate.

1.) If you look at the units for distance and time, and you know you want m/s for speed, then you can see division would be solution.

d = rt

40 = r(10)

r = 40/10

2.) d = rt

425 = (50)t

t = 8.5s

3.) d = rt

d = (35.25)(4)

d = 141km

4.) Add the distances together by using the equation twice for the way there and back.

216 = (48)t

t = 4.5

216 = (54)t

t = 4

4.5 + 4 = 8.5 hours

5.) Do the same thing from problem number four

210 = r(3.5)

r = 60m/h

130 = r(2.5)

r = 52mi/h

Average means the sum of the values divided by 2

0.5(60+52) = 56mi/h