# Velocity - 8th grade (13y) - math problems

The velocity of an object is the time rate of change of its position. Velocity is a specification of an object's speed and direction of motion (e.g. 20 m/s to the south).

In everyday use and in kinematics, the speed of an object is the magnitude of its velocity (the rate of change of its position) - scalar.

#### Number of problems found: 198

• Minute
Two boys started from one place. First went north at velocity 3 m/s and the second to the east with velocity 4 m/s. How far apart they are after minute?
• Pumps
Pump that draws water at velocity 3.5 liters per second water from a construction trench take 35 minutes. a) Find out how many minutes the water would run out of the trench pump that draws 7.4 liters of water per second. b) What is the pumping velocity wo
• Positional energy
What velocity in km/h must a body weighing 60 kg have for its kinetic energy to be the same as its positional energy at the height 50 m?
• An airplane
An airplane flies 1440 km in 2 1/4 hours. What is its average speed in km per hour?
• Wave parameters
Calculate the speed of a wave if the frequency is 336 Hz and the wavelength is 10 m.
• Working together
One worker performs work in 3 days, the second in 5 days. How much do they work together?
• RPM
An electric motor makes 3,000 revolutions per minutes. How many degrees does it rotate in one second?
• Bob traveled
Bob traveled 20 meters to Dave's house. He arrived in 3 minutes. What was his average speed for the trip.
• Magnitude of angle
What magnitude has an obtuse angle enclosed by the hands of clocks at 12:20 hours?
• Mail train
The speed of mail train is 1370 meter per minute. Express it in miles per hour correct to three significant figure . Given that 1 meter =39.37 inches.
• A bus
A bus is scheduled to travel a distance 121 km in 2 3/4 hours. What average rate of speed must be maintained to arrive on schedule?
• Two boats
The sightseeing boat sail at 25 km / h. The cruise take 6 hours. How long the another boat sails at 60 km/h?
• Saw
Blade circular saw with a diameter 42 cm turns 825 times per minute. Expresses his cutting speed in meters per minute.
• 3 pupils
3 pupils cleaned 10 meters of the stream in 1 hour. How many meters of the stream will clean 18 students in 4 hours?
• The fastest
The fastest boat can reach speeds more than 710% as fast as the Queen Mary 2. How would you express this number as a fraction and as a decimal?
• Two trains
Two trains go at each other. First at speed 40 km/h and the second at speed 60 km/h. At what distance will be 30 minutes before they will meet?
• Cable car
The cable car will carry 1280 passengers in 40 minutes. How many people will be transported in 2.5 hours?
• Doubling
The message is spreading that each day has doubled the number of people who know about it. All know message for 20 days. How long known it eighth people?
• Clock
How many times a day hands on a clock overlap?
• Timber log
The ship goes from point x to y. Downstream it takes 4 hours, upstream 6 hours. How long does it take from a point x to y a log?

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