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zysi [14]
3 years ago
14

A runner runs the first 400m of a race in 80s, the second 400m in 70s and the final 800m in 130s. What was her average speed for

this run?
Physics
1 answer:
-BARSIC- [3]3 years ago
5 0

Answer: The average speed is 5.71 m/s

Explanation:

The average speed in this run will be the quotient between the total distance that the runner traveled, and the total time it took.

Distance = 400m + 400m + 800m = 1600m

Time = 80s + 70s + 130s = 280s

Then the average speed is:

S = 1600m/280s = 5.71 m/s

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6 0
3 years ago
Read 2 more answers
What is the speed of a truck that travels 10 i’m in 10 minutes ?
fiasKO [112]

10km/10min is a legitimate speed. So is meters/sec, km/hour (kph), etc.  

Kph is very common for vehicles:  

10 km/10 min (60 min/hr) = 60 kph

7 0
3 years ago
1. A racing car with the driver weighs 1825 lb. Find the kinetic energy in ft*lb when traveling with a speed of 100 mi/hr.
Svetlanka [38]

Answer:

1. 610,000 lb ft

2. 490 J

Explanation:

1. First, convert mi/hr to ft/s:

100 mi/hr × (5280 ft / mi) × (1 hr / 3600 s) = 146.67 ft/s

Now find the kinetic energy:

KE = ½ mv²

KE = ½ (1825 lb / 32.2 ft/s²) (146.67 ft/s)²

KE = 610,000 lb ft

2. KE = ½ mv²

KE = ½ (5 kg) (14 m/s)²

KE = 490 J

6 0
3 years ago
Work is always done when
dusya [7]
Its option 3 an object has potential energy
5 0
2 years ago
Space debris left from old satellites and their launchers is becoming a hazard to other satellites. (a) Calculate the speed of a
Pie

Answer:

Part a)

v = 7407.1 m/s

Part b)

v_{rel} = 1.05 \times 10^4 m/s

Explanation:

Part a)

As we know that orbital velocity at certain height from the surface of Earth is given as

v = \sqrt{\frac{GM}{R+h}}

here we know that

M = 5.98 \times 10^{24} kg

R = 6.37 \times 10^6 m

h = 900 km = 9.0 \times 10^5 m

now we have

v = \sqrt{\frac{(6.67 \times 10^{-11})(5.98 \times 10^{24})}{6.37 \times 10^6 + 9.0 \times 10^5}}

v = 7407.1 m/s

Part b)

When a loose rivet is moving in same orbit but at 90 degree with the previous orbit path then in that case the relative speed of the rivet with respect to the satellite is given as

v_{rel} = \sqrt{2} v

v_{rel} = 1.05 \times 10^4 m/s

6 0
3 years ago
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