Try these... have fun!
1. Shona cycles at a speed of 8 km/h. How far has she travelled if she cycles for 4 hours?
S = 8 km/h
t = 4 hours
d = ?
d = S x t
= 8 x 4
= 32 km
She travelled 32 km.
2. Kelly runs from 4.50pm until 5.20pm at an average speed of 7 km/h. How far did she go?
S = 7 km/h
t = 30 min
d = ?
d = S x t
= 7 x ½ hour
= 3½ km
She went 3½ km.
3. Alan travels 100 km in 5 hrs. Find his speed in km/h.
d = 100 km
t = 5 hours
S = ?
S = d/t
= 100/5
= 20 km/h
Alan travelled at 20 km/h.
4. Find the speed of a train which travels 243 km in 2 hrs 15 mins.
d = 243 km
t = 2 hours 15 min
S = ?
S = d/t
= 243/2.25
= 108 km/h
The train travelled at 108 km/h.
5. Joanna drives for 400 km at a speed of 80 km/h. How long was her journey?
d = 400 km
S = 80 km/h
t = ?
t = d/S
= 400/80
= 5 hours
Her journey was 5 hours long.
6. (Using a different unit of measurement) Scott cycles at 4 mph and covers a distance of 13 miles. How long does his journey take?
S = 4 mph
d = 13 miles
t = ?
t = d/S
= 13/4
= 3.25
His journey takes 3 hours and 15 minutes.
S = 8 km/h
t = 4 hours
d = ?
d = S x t
= 8 x 4
= 32 km
She travelled 32 km.
2. Kelly runs from 4.50pm until 5.20pm at an average speed of 7 km/h. How far did she go?
S = 7 km/h
t = 30 min
d = ?
d = S x t
= 7 x ½ hour
= 3½ km
She went 3½ km.
3. Alan travels 100 km in 5 hrs. Find his speed in km/h.
d = 100 km
t = 5 hours
S = ?
S = d/t
= 100/5
= 20 km/h
Alan travelled at 20 km/h.
4. Find the speed of a train which travels 243 km in 2 hrs 15 mins.
d = 243 km
t = 2 hours 15 min
S = ?
S = d/t
= 243/2.25
= 108 km/h
The train travelled at 108 km/h.
5. Joanna drives for 400 km at a speed of 80 km/h. How long was her journey?
d = 400 km
S = 80 km/h
t = ?
t = d/S
= 400/80
= 5 hours
Her journey was 5 hours long.
6. (Using a different unit of measurement) Scott cycles at 4 mph and covers a distance of 13 miles. How long does his journey take?
S = 4 mph
d = 13 miles
t = ?
t = d/S
= 13/4
= 3.25
His journey takes 3 hours and 15 minutes.
Speed (2) - Thanks Kong and Ponden
1. John travels by car to his university at 60 km/h. The distance to his university is 249 km. How long does the journey take?
S = 60 km/h
D = 249 km/h
T = D/S
= 249/60
= 4.15 hrs
= 4 hrs 9 mins
2. Suzie drives from Phuket to Bangkok in 15 hours. The distance to Bangkok is 900 km. What is her average speed?
T = 15 hrs
D = 900km
S = D/T
= 900/15
= 60 km/h
3. Peter swims every morning from 6:15 am to 7:30 am. Peter swims at an average speed of 3.5 km/h. What distance does Peter swim every morning?
6:15 am ---> 7:30 am = 1 hour 15 mins OR 1 1/4 hrs
T = 1 1/4 hrs
S = 3.5 km/h
D = S x T
= 3.5 x 1.25 OR 7/2 x 5/4
= 4.375 km OR 4 3/8 km
4. Usian Bolt (the famous Olympic sprinter) runs 100 m in 9.58 seconds. How fast does he run? Write your answer in m/sec (meters per second).
D = 100 m
T = 9.58 s
S = 100/9.58
= 10.44 m/s
S = 60 km/h
D = 249 km/h
T = D/S
= 249/60
= 4.15 hrs
= 4 hrs 9 mins
2. Suzie drives from Phuket to Bangkok in 15 hours. The distance to Bangkok is 900 km. What is her average speed?
T = 15 hrs
D = 900km
S = D/T
= 900/15
= 60 km/h
3. Peter swims every morning from 6:15 am to 7:30 am. Peter swims at an average speed of 3.5 km/h. What distance does Peter swim every morning?
6:15 am ---> 7:30 am = 1 hour 15 mins OR 1 1/4 hrs
T = 1 1/4 hrs
S = 3.5 km/h
D = S x T
= 3.5 x 1.25 OR 7/2 x 5/4
= 4.375 km OR 4 3/8 km
4. Usian Bolt (the famous Olympic sprinter) runs 100 m in 9.58 seconds. How fast does he run? Write your answer in m/sec (meters per second).
D = 100 m
T = 9.58 s
S = 100/9.58
= 10.44 m/s
Word problems with fractions.
Remember to draw a model to help you see what you need to do.
1 .Rose's average speed for a 45 km journey was 75 km/h. She took 21 minutes for the first 2/3 of her journey. What was her speed for the last 1/3 of the journey?
Given Total Distance (45 km) and Avg. Speed (75 km/h), we can work out Total Time.
T = D / S
T = 45 / 75 = 0.6 hrs
0.6 hrs = 36 minutes!!!
Now look back at the model. If TOTAL TIME is 36 minutes, and the first 2/3 is 21 minutes. Then the last 1/3 is (36mins – 21mins) = 15 minutes.
Our TOTAL DISTANCE is 45km. that means that 1/3 of the TOTAL DISTANCE is (45 / 3) = 15 km.
So now for the last 1/3 of the model we have a TIME and a DISTANCE. We can now work out the speed.
S = D/T
S = 15 / 0.25 (REMEMBER!! Our speed is in km/h so our time must be in hours. 15 mins = 0.25 hrs)
S = 60 km/h
The Avg. speed for the final 1/3 of the journey was 60 km/h.
T = D / S
T = 45 / 75 = 0.6 hrs
0.6 hrs = 36 minutes!!!
Now look back at the model. If TOTAL TIME is 36 minutes, and the first 2/3 is 21 minutes. Then the last 1/3 is (36mins – 21mins) = 15 minutes.
Our TOTAL DISTANCE is 45km. that means that 1/3 of the TOTAL DISTANCE is (45 / 3) = 15 km.
So now for the last 1/3 of the model we have a TIME and a DISTANCE. We can now work out the speed.
S = D/T
S = 15 / 0.25 (REMEMBER!! Our speed is in km/h so our time must be in hours. 15 mins = 0.25 hrs)
S = 60 km/h
The Avg. speed for the final 1/3 of the journey was 60 km/h.
2. Michael travelled 2/5 of his journey at 50 km/h. The next 1/5 of his journey he travelled at 40 km/h. The remaining 40 km he covered in half an hour. How much time did he take for the whole journey?
Draw a model with ALL given information like the one above.
Start with what you can calculate.
We know for 2/5 of the journey the Distance is 40 km. So we know that each 1/5 of the journey is (40 / 2) = 20 km. So TOTAL DISTANCE is (20 km x 5) = 100 km. * fill in on the model 20 km between each 1/5 of the journey!
The question asks us to work out TOTAL TIME. We already have the time for the last 2/5 of the journey (30 mins). We now need to work out the time for the other 3/5.
For the FIRST 2/5 of the journey we have a SPEED and a DISTANCE. So we can work out TIME.
D = (20km x 2) = 40 km
S = 50 km/h
T = D / S
T = 40 / 50 = 0.8 hrs = 48 mins.
For the next 1/5 of the journey we have a SPEED and a DISTANCE, so again can work out TIME.
D = 20 km
S = 40 km/h
T = D / S
T = 20 / 40 = 0.5 hrs = 30 mins.
So TOTAL TIME is all the times ADDED together.
30 mins + 48 mins + 30 mins
= 1 hr 48 mins.
The total time for the whole journey was 1 hour 48 minutes.
Start with what you can calculate.
We know for 2/5 of the journey the Distance is 40 km. So we know that each 1/5 of the journey is (40 / 2) = 20 km. So TOTAL DISTANCE is (20 km x 5) = 100 km. * fill in on the model 20 km between each 1/5 of the journey!
The question asks us to work out TOTAL TIME. We already have the time for the last 2/5 of the journey (30 mins). We now need to work out the time for the other 3/5.
For the FIRST 2/5 of the journey we have a SPEED and a DISTANCE. So we can work out TIME.
D = (20km x 2) = 40 km
S = 50 km/h
T = D / S
T = 40 / 50 = 0.8 hrs = 48 mins.
For the next 1/5 of the journey we have a SPEED and a DISTANCE, so again can work out TIME.
D = 20 km
S = 40 km/h
T = D / S
T = 20 / 40 = 0.5 hrs = 30 mins.
So TOTAL TIME is all the times ADDED together.
30 mins + 48 mins + 30 mins
= 1 hr 48 mins.
The total time for the whole journey was 1 hour 48 minutes.
3. A train departed Singapore at 10.40 a.m. and arrived in Malacca, 250 km away, at 2.00 p.m.. Along the way, it made 5 stops of 10 minutes each. Albert left Singapore in his car at the same time as the train and arrived in Malacca also at the same time but without stopping. How much faster was the train's average speed compared to that of Albert's car?
To work out how much faster the train was we need to compare the average speed’s of the train and the car.
Train:
To work out the SPEED for the train we need the TIME and the DISTANCE. S = D /T
We are given a DISTANCE of 250 km.
For TIME we know that from 10.40am --> 2pm is = 3 hrs 20 mins.
BUT!!! The train stopped 5 times for 10 mins each time.
5 x 10 = 50 mins.
So we know that for 50 mins the train wasn’t moving, so we need to subtract that from TOTAL TIME.
3 hrs 20 mins – 50 mins = 2 hrs 30 mins.
So 2 hrs 30 mins was the TOTAL TIME that’s the TRAIN was travelling! We now have a TIME and a DISTANCE for the train.
T = 2.5 hrs
D = 250 km
S = D / T
S = 250 / 2.5 = 100 km/h
CAR:
The car left at the SAME TIME as the train (10.40am) and arrived at the SAME TIME (2pm) as the train, and it did not stop. So time is just 10.40am --> 2pm which is 3 hrs 20 mins.
The distance is the same as the train as well because they BOTH travelled from Singapore to Mallaca.
D = 250 km
T = 3 1/3 hrs OR 3.33 hrs
S = D / T
S = 250 / 3.33 = 75 km/h
So the speed of the train is 100 km/h and the speed of the car is 75 km/h. 100 – 75 = 25 km/h.
So the train is 25 km/h FASTER than the car.
Train:
To work out the SPEED for the train we need the TIME and the DISTANCE. S = D /T
We are given a DISTANCE of 250 km.
For TIME we know that from 10.40am --> 2pm is = 3 hrs 20 mins.
BUT!!! The train stopped 5 times for 10 mins each time.
5 x 10 = 50 mins.
So we know that for 50 mins the train wasn’t moving, so we need to subtract that from TOTAL TIME.
3 hrs 20 mins – 50 mins = 2 hrs 30 mins.
So 2 hrs 30 mins was the TOTAL TIME that’s the TRAIN was travelling! We now have a TIME and a DISTANCE for the train.
T = 2.5 hrs
D = 250 km
S = D / T
S = 250 / 2.5 = 100 km/h
CAR:
The car left at the SAME TIME as the train (10.40am) and arrived at the SAME TIME (2pm) as the train, and it did not stop. So time is just 10.40am --> 2pm which is 3 hrs 20 mins.
The distance is the same as the train as well because they BOTH travelled from Singapore to Mallaca.
D = 250 km
T = 3 1/3 hrs OR 3.33 hrs
S = D / T
S = 250 / 3.33 = 75 km/h
So the speed of the train is 100 km/h and the speed of the car is 75 km/h. 100 – 75 = 25 km/h.
So the train is 25 km/h FASTER than the car.
4. A woman fell from the top of a building 280 metres tall. 3 seconds later, Superman jumped off the top of the same building to save her. It took Superman 2 seconds to rescue her just before she hit the ground. What was Superman's average speed?
To work out Supermans Avg. Speed we need his Total time travelling and Total distance covered. We are given both of these. Be carefull not to include the 3 seconds it took before superman jumped after her, because superman had not started travelling yet. He only travelled for 2 seconds.
D = 280 m
T = 2 seconds
S = D / T
S = 280 / 2 = 140 m/s
Supermans Avg. Speed was 140 m/s.
*remember your unit of speed is m/s NOT km/h.
WELL DONE if you got these questions right!! They were very tricky!!
D = 280 m
T = 2 seconds
S = D / T
S = 280 / 2 = 140 m/s
Supermans Avg. Speed was 140 m/s.
*remember your unit of speed is m/s NOT km/h.
WELL DONE if you got these questions right!! They were very tricky!!