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ddd [48]
3 years ago
9

7. A runner runs on the track field with a velocity of 20 m/s and it is known that her momentum is

Physics
1 answer:
Dennis_Churaev [7]3 years ago
4 0

Answer:

Weight of the runner is 60 kilograms

Explanation:

Momentum is the product of weight and velocity.

The formula is : p=mv   where m is mass in kg and v is velocity in m/s

Given in the question ;

v= 20 m/s  and p=1200 kg*m/s

Applying the formula as;

p= mv

1200 = m * 20

1200/20 = m

60 kg = m

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A bicycle rider pushes a 13kg bicycle up a steep hill. the incline is 24 degree and the road is 275m long. the rider pushes the
Digiron [165]

Answer:

A. W = 6875.0 J.

B. W = -14264.6 J.

Explanation:

A. The work done by the rider can be calculated by using the following equation:

W_{r} = |F_{r}|*|d|*cos(\theta_{1})

Where:                

F_{r}: is the force done by the rider = 25 N

d: is the distance = 275 m

θ: is the angle between the applied force and the distance

Since the applied force is in the same direction of the motion, the angle is zero.

W_{r} = |F_{r}|*|d|*cos(0) = 25 N*275 m = 6875.0 J

Hence, the rider does a work of 6875.0 J on the bike.

B. The work done by the force of gravity on the bike is the following:

W_{g} = |F_{g}|*|d|*cos(\theta_{2})  

The force of gravity is given by the weight of the bike.

F_{g} = -mgsin(24)     

And the angle between the force of gravity and the direction of motion is 180°.

W_{g} = |mgsin(24)|*|d|*cos(\theta_{2})  

W_{g} = 13 kg*9.81 m/s^{2}*sin(24)*275 m*cos(180) = -14264.6 J  

The minus sign is because the force of gravity is in the opposite direction to the motion direction.

Therefore, the magnitude of the work done by the force of gravity on the bike is 14264.6 J.  

I hope it helps you!                                                                                          

3 0
3 years ago
If the distance d (in meters) traveled by an object in time t (in seconds) is given by the formula d = A + Bt^2, the SI units of
Yuliya22 [10]

Answer:

The SI units of the “A” is m (meters)

The SI units of the “B” is m/s^2

Explanation:

Given the distance = d meters.

Time taken to travel = t (seconds)

Function of the distance, d = A + Bt^2

Now we have given the above information and from the given distance function, we have to find the SI units of the A and B. Here, below are the SI units.

Thus, the SI units of the “A” is = m (meters)

The SI units of the “B” is = m/s^2

6 0
3 years ago
A copper wire of resistivity 2.6 × 10-8 Ω m, has a cross sectional area of 35 × 10-4 cm2
KengaRu [80]

Answer:

the length of the wire is 134.62 m.

Explanation:

Given;

resistivity of the copper wire, ρ = 2.6 x 10⁻⁸ Ωm

cross-sectional area of the wire, A  = 35 x 10⁻⁴ cm² = ( 35 x 10⁻⁴) x 10⁻⁴ m²

resistance of the wire, R = 10Ω

The length of the wire is calculated as follows;

R = \frac{\rho L}{A} \\\\L = \frac{RA}{\rho} \\\\L= \frac{10 \times (35\times 10^{-4}) \times 10^{-4}}{2.6 \times 10^{-8}} \\\\L = 134.62 \ m

Therefore, the length of the wire is 134.62 m.

6 0
3 years ago
Which one of the following SI base units is not matched to the correct unit of measurement?
laiz [17]
<span><span>A.    </span>Length: km<span>


The Si units of all the left measurements are true thus, in length the typical and standard SI unit is meter. SI units, also called as International Standard of Units, is composed of the following systematized units of physical measure which include, mole (amount of substance), candela (luminous intensity), kelvin (temperature), ampere (electric current), second (time), kilogram (mass), and meter (length). Hence, these measures spheres in multiplication or division by power of 10, increase or decrease in measure.</span></span>  



3 0
3 years ago
Which statement explains why a short eyeball causes farsighted
snow_lady [41]
I think the correct answer would be the rays of light focus behind the retina. It is a condition called farsightedness or hyperopia.  Due to his, objects that are close to the eyes seems to be blurry and as it worsens everything would become blurry to the eye.
8 0
3 years ago
Read 2 more answers
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