Ask question

Ask question

All categories

3 years ago

15

The average speed of a runner in a 400.-meter race is 8.0 meters per second. how long did it take the runner to complete the rac

e?

2 answers:

marusya05 [52]3 years ago

7 0

Answer:

Time taken, t = 50 seconds

Explanation:

It is given that,

Distance covered by the runner, d = 400 m

Average speed of the runner, v = 8 m/s

Let t is the time taken by the runner to complete the race. It can be calculated using the concept of average velocity. The total distance covered divided by total time is called average speed of the runner as :

$v=\dfrac{d}{t}$

$t=\dfrac{d}{v}$

$t=\dfrac{400\ m}{8\ m/s}$

t = 50 seconds

So, the time taken by the runner to complete the race is 50 seconds. Hence, this is the required solution.

vivado [14]3 years ago

4 0

D = 400 m
v = 8m/s
t = ?
v=d/t
t= d/v
t= 400/8
t= 50s

You might be interested in

Uses of hydrometer in points

Arisa [49]

Answer:

A hydrometer is an instrument used to determine specific gravity. It operates based on the Archimedes principle that a solid body displaces its own weight within a liquid in which it floats. Hydrometers can be divided into two general classes: liquids heavier than water and liquids lighter than water

7 0

2 years ago

Two generators use the same magnetic field and operate at the same frequency. Each has a single-turn circular coil. One generato

Volgvan

Answer:

The coil radius of other generator is 5.15 cm

Explanation:

Consider the equation for induced emf in a generator coil:

EMF = NBAω Sin(ωt)

where,

N = No. of turns in coil

B = magnetic field

A = Cross-sectional area of coil = π r²

ω = angular velocity

t = time

It is given that for both the coils magnetic field, no. of turn and frequency is same. Since, the frequency is same, therefore, the angular velocity, will also be same. As, ω = 2πft.

Therefore, EMF for both coils or generators will be:

EMF₁ = NBπr₁²ω Sin(ωt)

EMF₂ = NBπr₂²ω Sin(ωt)

dividing both the equations:

EMF₁/EMF₂ = (r₁/r₂)²

r₂ = r₁ √(EMF₂/EMF₁)

where,

EMF₁ = 1.8 V

EMF₂ = 3.9 V

r₁ = 3.5 cm

r₂ = ?

Therefore,

r₂ = (3.5 cm)√(3.9 V/1.8 V)

<u>r₂ = 5.15 cm</u>

3 0

2 years ago

Law Incorporation [45]

Answer:

1 is c 2 is a and 3 is b hope that helped!

4 0

3 years ago

A 3-m-high, 7-m-wide rectangular gate is hinged at the top edge and is restrained by a fixed ridge. Determine the hydrostatic fo

Shalnov [3]

Answer:

The Hydrostatic force is $F = 137.2 kN$

The location of pressure center is $Z = 1.333 \ m$

Explanation:

From the question we are told that

The height of the gate is $h = 3 \ m$

The weight of the gate is $w = 7 \ m$

The height of the water is $h_w = 2 \ m$

The density of water is $\rho_w = 1000 \ kg/m^3$

Note used $h_w$ for height of water and height of gate immersed by water since both have the same value

The area of the gate immersed in water is mathematically represented as

$A = h_w * w$

substituting values

$A = 2* 7$

$A = 14 \ m^2$

The hydrostatic force is mathematically represented as

$F = \rho_w * g * h_f * A$

Where

$h_f =h- h_w$

$h_f =3 -2$

$h_f = 1\ m$

So

$F = 1000 * 9.8 * 1 * 14$

$F = 137.2 kN$

The center of pressure is mathematically represented as

$Z = h_f + \frac{I_g}{h_f * A}$

Where $I_g$ is the moment of inertia of the gate which mathematically represented as

$I_g = \frac{w * h_w^2}{12}$

The $h_w$ is the height of gate immersed in water

$I_g = \frac{7 * 2^2 }{12}$

$I_g = 4.667\ kg m^2$

Thus

$Z = 1 + \frac{4.66}{1 * 14}$

$Z = 1.333 \ m$

3 0

2 years ago

An object has a velocity of 8 m/s and a kinetic energy of 480 j what is the mass of the object

dedylja [7]

We Know,

K.E. = 1/2 mv²

480 = 1/2 (m)(8)²

m = 960/64

m = 15 Kg

So, the mass of the object is 15 Kg

7 0

3 years ago

Read 2 more answers