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laila [671]
2 years ago
13

7.

Physics
1 answer:
kiruha [24]2 years ago
5 0

Answer:

The given figure shows two men M and N facing two flat and hard walls, wall 1 and wall 2. Man N fires a gun. Man M hears two echoes, one from wall 1 and second from wall 2. The speed of sound in

air is given to be 325 m/s. After the firing of the gun by the man N, the man M will hear the first echo in how many seconds?

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An athlete whose mass is 87.0 kg is performing weight-lifting exercises. Starting from the rest position, he lifts, with constan
expeople1 [14]

Answer: X = 52,314.12 N

Explanation: Let X be the force the feet of the athlete exerts on the floor.

According to newton's third law of motion the floor gives an upward reaction based on the weight of the athlete and the barbell which is known as the normal reaction ( based on the mass of the athlete and the barbell)

Mass of athlete = 87kg, mass of barbell = 600/ hence total normal reaction from the floor = 87* 61.22/ 9.8 *9.8 = 52,200N.

The athlete lifts the barbell from rest thus making it initial velocity u=0, distance covered = S = 0.65m and the time taken = 1.3s

The acceleration of the barbell is gotten by using the equation of constant acceleration motion

S= ut + 1/2at²

But u = 0

S = 1/2at²

0.65 = 1/2 *a (1.3)²

0.65 = 1.69 * a/2

0.65 * 2 = 1.69 * a

a = 0.65 * 2/ 1.69

a = 0.77m/s²

According to newton's second law of motion

Resultant force = mass * acceleration

And resultant force in this case is

X - 52,200 = (87 + 61.22) * 0.77

X - 52,200 = 148.22 * 0.77

X - 52, 200 = 114.132

X = 114.132 + 52,200

X = 52,314.12 N

6 0
3 years ago
.
insens350 [35]

Answer:

-\frac{1}{2}

Diverging lens

Explanation:

Given parameters:

Power of lens  = -2.0D

Unknown:

Focal length  = ?

Solution:

The power of lens is the reciprocal of the focal length;

   P  = \frac{1}{f}

where  f is the focal length

 f  = \frac{1}{P}   = -\frac{1}{2}

The lens is a diverging lens

8 0
2 years ago
An 800-N billboard worker stands on a 4.0-m scaffold weighing 500 N and supported by vertical ropes at each end. How far would t
Lynna [10]

Answer:

2.5 m

Explanation:

Weight of billboard worker = 800 N

Number of ropes = 2

Length of scaffold = 4 m

Weight of scaffold = 500 N

Tension in rope = 550 N

The sum of the torques will be

-800(4-x)-500\times 2+550\times 4=0\\\Rightarrow -800(4-x)=500\times 2-550\times 4\\\Rightarrow -800(4-x)=-1200\\\Rightarrow -x=\dfrac{1200}{800}-4\\\Rightarrow -x=-2.5\\\Rightarrow x=2.5\ m

The position of the person will be 2.5 m

7 0
3 years ago
This DNA strand consists of eight pairs of nitrogenous bases. How many different sequences of eight bases can you make?
BaLLatris [955]

Answer:

assuming that there is an equal amount of each base, you can make 65,536 bases

Explanation:

Adenine(A) Guanine(G) Thymine(T) and Cytosine(C) are the 4 nitrogen bases.

8 0
3 years ago
Why can't humans breathe in space?​
11111nata11111 [884]

Answer:

There is no atmspheric pressure

4 0
2 years ago
Read 2 more answers
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