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maks197457 [2]
3 years ago
10

A boy in a wheelchair (total mass 56.0 kg) has speed 1.40 m/s at the crest of a slope 2.30 m high and 12.4 m long. At the bottom

of the slope his speed is 6.40 m/s. Assume air resistance and rolling resistance can be modeled as a constant friction force of 41.0 N. Find the work he did in pushing forward on his wheels during the downhill ride.
Physics
1 answer:
MatroZZZ [7]3 years ago
5 0

Answer:

338.16 J

Explanation:

We are given that

Total mass ,m=56 kg

v_0=1.4 m/s

h=2.3 m

l=12.4 m

v=6.4 m/s

Friction force,f=41 N

We have to find the work done by boy in pushing the forward on his wheels during the downhill ride.

According to law of conservation of energy

\frac{1}{2}mv^2_0+mgh+W=\frac{1}{2}mv^2+W_f

W=\frac{1}{2}mv^2+W_f-\frac{1}{2}mv^2_0-mgh

W=\frac{1}{2}m(v^2-v^2_0)+fl-mgh

Where g=9.8 m/s^2

W=\frac{1}{2}(56)((6.4)^2-(1.4)^2)+41(12.4)-56\times 9.8\times 2.3

W=338.16 J

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Alex73 [517]

Answer:

d = 23.75 m

The zebra has gone 23.75m after 5 seconds.

Corrected question;

A zebra starts from rest and accelerates at 1.9 m/s2. How far has the zebra gone after 5 seconds.

Explanation:

From the equation of motion;

d = vt + 0.5at^2 .........1

Where;

d = displacement

v = initial velocity = 0

t = time taken= 5 seconds

a = acceleration = 1.9 m/s^2

Substituting the given values into equation 1;

d = 0(5) + 0.5(1.9×5^2)

d = 0.5(1.9×5^2)

d = 23.75 m

The zebra has gone 23.75m after 5 seconds.

3 0
4 years ago
Bowl of water A bowl full of water is sitting out in a pouring rainstorm. Its surface area is 500 cm2. The rain is coming straig
vova2212 [387]

Answer: 4.9 x 10-3 N

Explanation:

A = 500cm^2 = 5 x 10^-2 m^2

V = 5 m/s

R = 10^-3 g/cm^2.sec = 10^-2kg/m^2 . sec

Prain water = R / V = 10^-2 / 5 = 2 x 10-3 kg/m^3

For the stationary bowl,

dm/dt =pAv= RA

F= dp/dt = (dm/dt) v = RAv = 2.5 x 10^-3 N

Bowl moving upwards to speed u = 2 m/s

dm/dt = pA ( v + u) / v

F = dp/dt = (dm/dt)(v+u) = RA (v+u)^2 / v = 4.9 x 10^-3 N

5 0
3 years ago
The electric field in a region is uniform (constant in space) and given by E-( 148.0 1 -110.03)N/C. An additional charge 10.4 nC
enyata [817]

Answer:

The y-component of the electric force on this charge is F_y = -1.144\times 10^{-6}\ N.

Explanation:

<u>Given:</u>

  • Electric field in the region, \vec E = (148.0\ \hat i-110.0\ \hat j)\ N/C.
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where, \hat i,\ \hat j are the unit vectors along the positive x and y axes respectively.

The electric field at a point is defined as the electrostatic force experienced per unit positive test charge, placed at that point, such that,

\vec E = \dfrac{\vec F}{q}\\\therefore \vec F = q\vec E\\=(10.4\times 10^{-9})\times (148.0\ \hat i-110.0\ \hat j)\\=(1.539\times 10^{-6}\ \hat i-1.144\times 10^{-6}\ \hat j)\ N.

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3 years ago
This problem has been solved!
AleksAgata [21]

Answer:the velocity is zero, the acceleration is directed downward, and the force of gravity acting on the ball is directed downward.

Explanation:

When a ball is tossed vertically upwards, it reaches its maximum point. This maximum point is known as the maximum height of the ball. At this maximum height, its velocity is zero, its acceleration is directed downwards and the force of gravity acting in the ball is directed downwards towards the earth.

6 0
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What does the vibrating object do to the air particles around it ?
Westkost [7]

Answer:

When an object vibrates, it causes movement in surrounding air molecules. These molecules bump into the molecules close to them, causing them to vibrate as well. This makes them bump into more nearby air molecules.

7 0
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