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sdas [7]
4 years ago
9

A cross-country skier can complete a 7.5 km race in 45 min. What is the skier’s average speed?

Physics
2 answers:
Triss [41]4 years ago
8 0

<u>Answer</u>

2.7778 m/s


<u>Explanation</u>

Speed is rate of change of distance with time.

It is the distance covered in a unit time.  SI units of speed in m/s. Other units are Km/h, knots e.t.c

Average speed  = (total distance covered) / (total time taken)

                             = 7.5 Km / 45 Min

                             =  1/6 Km/Min

Or,

7.5Km = (7.5 × 1000) m = 7500 m

45 min = 45 × 60 2700 seconds

Average speed = 7500/2700

                           = 2.7778 m/s

Alecsey [184]4 years ago
7 0
To calculate for the average speed, we simply divide the total distance covered by the time it takes to travel that distance. In this case, we simply divide 7.5 km with 45 min. Therefore, the skier's average speed is 0.1667 km/min. Hope this helps.
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Given what we know, we can confirm that the tensional force of a system can in theory be changed without diminishing its force through the use of an ideal pulley.

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Therefore, we can confirm that the only known way to change the direction of a force without diminishing its value would be through the use of a frictionless and massless pulley system otherwise known as an ideal pulley.

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4 0
3 years ago
The rocket is fired vertically and tracked by the radar station shown. When θ reaches 66°, other corresponding measurements give
Flauer [41]

Answer:

velocity = 1527.52 ft/s

Acceleration = 80.13 ft/s²

Explanation:

We are given;

Radius of rotation; r = 32,700 ft

Radial acceleration; a_r = r¨ = 85 ft/s²

Angular velocity; ω = θ˙˙ = 0.019 rad/s

Also, angle θ reaches 66°

So, velocity of the rocket for the given position will be;

v = rθ˙˙/cos θ

so, v = 32700 × 0.019/ cos 66

v = 1527.52 ft/s

Acceleration is given by the formula ;

a = a_r/sinθ

For the given position,

a_r = r¨ - r(θ˙˙)²

Thus,

a = (r¨ - r(θ˙˙)²)/sinθ

Plugging in the relevant values, we obtain;

a = (85 - 32700(0.019)²)/sin66

a = (85 - 11.8047)/0.9135

a = 80.13 ft/s²

4 0
3 years ago
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9 0
3 years ago
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Doc Brown has calculated his Delorean can accelerate at a rate of 2.52 m/s/s. How
GREYUIT [131]

Answer:

304.89m

Explanation:

Given

acceleration a = 2.52m/s²

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4 years ago
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