Answer:
His speed, in metres per second, is approximately 10m/s. The correct option is B.
Explanation:
Speed is defined as the rate in which an object cover a distance in a given time. It is measured in meters per second ( m/s). From the question, the jogger covered a distance of 3Km which when converted to meter is 3000meters in a given time 5 minutes which is 300seconds. The calculation of his speed in meter per second is shown below:
Distance= 3Km to meters ( as 1000meters = 1Km). Therefore 3× 1000 = 3000m
Time= 5 minutes to seconds ( as 1 minute = 60 Seconds). Therefore 5× 60= 300.
Speed= distance/ time
= 3000/300
= 10m/s
Therefore his speed, in metres per second, is approximately 10.
Answer:
The velocity of the train is 82.8 km/h
Explanation:
The equation for the position of the train and the car is as follows:
x = x0 + v · t
Where:
x = position at time "t".
x0 = initial position.
v = velocity.
t = time.
First, let´s calculate the distance traveled by the car in 60 s (1/60 h). Let´s place the origin of the frame of reference at the front of the train when it starts to pass the car so that the initial position of the car is 0 (x0 = 0 m):
x = 0 m + 72 km/h · (1/60) h
x = 1.2 km.
Then, if the whole train passes the car at that time, the position of the front of the train at that time will be 1.2 km + 0.18 km = 1.38 km.
Then using the equation of position we can obtain the velocity:
x = x0 + v · t
1.38 km = 0 m + v · (1/60) h
1.38 km / (1/60) h = v
v = 82.8 km/h
The velocity of the train is 82,8 km/h
The same result could be obtained using the rear of the train. You only have to identify where the rear is at t = 0 and where it is at t = 60 s.
Try it!
A ) v = v o + a t ( the acceleration will be negative )
9.50 = 16.0 + a * 1.2
a * 1.2 = -16.0 + 9.50
a * 1.2 = - 6.5
a = - 6.5 : 1.2
a = - 5.4167 m/s²
F = m * a = 950 kg * 5.4167 m/s²
F = 5,145.8 N ( the average force exerted on a car during braking )
b ) d = v o - a t² / 2
d = 16.0 * 1.2 - ( 5.4167 * 1.2² / 2 ) =
= 19.20 - 3.90 = 15.30 m
Convert the units of power,W = 7 hp = 7 * 745.69 = 5219.83 WCalculate the power input to the pump using the efficiency of the pump equationn=Wpump/Wshaft
Substitute 0.82 for n and 5219.83 for Wshaft0.82=Wpump/5219.83 Wpump=0.82*5219.83=4280.26 WCalculate the mass flow ratein=Wpump/(gz_2 )Where g is the acceleration due to gravity, and z_2 is the elevation of water. Substitute 4280.26 for Wpump, 9.81 m/s^2 for g, and 19m for z_2in = 4280.26 / 9.81 * 19 = 22.9640 m^3/sCalculate the volume flow rate of waterV=m/ρWhere ρ is the density of water. Substitute 22.9640 m^3/s for in and 1000 m^3/kg for ρ, we get V = 22.9640 / 1000 = 0.0230 kg/sTherefore, the volume flow rate of water is 0.0230 kg/s
sound travels through air at around 340 - 350 m/s.
to cover 52 meters takes it, say, (52/345) = about 0.15 second
This would be the same time-lag even if it were not a major-league game,
except that you might not be able to get a seat 52 meters from home plate
at a little league or t-ball game.
