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Georgia [21]
3 years ago
11

A tortoise can run with a speed of 0.14 m/s, and a hare can run 20 times as fast. In a race, they both start at the same time, b

ut the hare stops to rest for 1.0 minutes. The tortoise wins by a shell (30 cm). (a) how long does the race take? S (b) what is the length of the race?
Physics
1 answer:
Reptile [31]3 years ago
4 0

speed of tortoise is given as v1 = 0.14 m/s

speed of hare is given as v2 = 20*0.14 = 2.8 m/s

now let say the total length of the path is "d"

so the total time taken by the tortoise to cover this

t = \frac{d}{0.14}

now given that hare took rest for 1 min

so total time of run for hare is (t - 60)s

so the distance that hare covered is given by

d - 0.30 = 2.8 * (t - 60)

now by above two equations

d - 0.30 = 2.8 * \frac{d}{0.14} - 168

168 - 0.30 = (20 - 1)d

d = 8.82 m

and the time t is given by

t = \frac{8.82}{0.14}

t = 63 s

so part a)

t = 63 s

part b)

d = 8.82 m

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A block of mass m = 2.0 kg lies on a rough ramp that is inclined at an angle θ = 20oto the horizontal. A force F of magnitude 5.
Marina86 [1]

Answer:

a) 0.64 b) 2.17m/s^2 c) 8.668joules

Explanation:

The block was on the ramp, the ramp was inclined at 20degree. A force of 5N was acting horizontal to the but not parallel to the ramp,

Frictional force = horizontal component of the weight of the block along the ramp + the applied force since the block was just about move

Frictional force = mgsin20o + 5N = 6.71+5N = 11.71

The force of normal = the vertical component of the weight of the block =mgcos20o = 18.44

Coefficient of static friction = 11.71/18.44= 0.64

Remember that g = acceleration due to gravity (9.81m/s^2) and m = mass (2kg)

b) coefficient of kinetic friction = frictional force/ normal force

Fr = 0.4* mgcos 20o = 7.375N

F due to motion = ma = total force - frictional force

Ma = 11.71 - 7.375 = 4.335

a= 4.335/2(mass of the block) = 2.17m/s^2

C) work done = net force *distance = 4.335*2= 8.67Joules

8 0
3 years ago
Einstein and Lorentz, being avid tennis players, play a fast-paced game on a court where they stand 20.0 m from each other. Bein
kobusy [5.1K]

Answer:

Explanation:

a ) Kinetic energy of ball = 1/2 m v² , m is mass of the ball and v is its velocity

= 1/2 x .058 x 80²

= 185.6 J .

b ) The velocity of ball is very high so we shall find out the relativistic kinetic energy , the formula is given below

kinetic energy = mc² (    \frac{1}{\sqrt{1-\frac{v^2}{c^2} } } -1  )

= mc² x \frac{1}{\sqrt{1-\frac{v^2}{c^2} } }   - mc²

= .058 x 9 x 10¹⁶ x \frac{1}{\sqrt{1-\frac{1.8^2}{3^2} } }  - .058 x 9 x 10¹⁶

= .058 x 9 x 10¹⁶ x 1 / .8 - .058 x 9 x 10¹⁶

.058 x 9 x 10¹⁶ ( 1.25 - 1 )

= .058 x 9 x 10¹⁶ x .25

= .1305 x 10¹⁶

= 13.05 x 10¹⁴ J .

4 0
4 years ago
A shell is fired from the ground with an initial speed of 1.74 ✕ 103 m/s at an initial angle of 58° to the horizontal.
ValentinkaMS [17]

Answer:

a) horizontal range s=277671.77 m

b) time the shell is in motion 301.143 s

Explanation:

Is a parabolic movement so the velocity have two components:

v = 1.74 x 10^{3}  ( \frac{m}{s} )

\alpha = 58°

v_{y} =v*Sen (\alpha )\\v_{x} =v*Cos (\alpha )

v_{y} =1740*Sen (58 )\\v_{x} =1740*Cos (58)

v_{y} = 1475.603 \frac{m}{s}\\v_{x} = 922.059 \frac{m}{s}\\

t= \frac{2*v_{y} }{g}

t= \frac{2*1475.603 }{9.8}

t= 301.143 s

v= \frac{s}{t} \\s= v_{x}*t

s= 922.059 \frac{m}{s} * 301.143 s

s = 277671.77 m

4 0
4 years ago
Which are long chains of subunits formed by the process of polymerization? Check all that apply.
vampirchik [111]

The long chains of subunits formed by the process of polymerization are:

B. Macromolecules

D. Polymers

F. DNA

6 0
4 years ago
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tiny-mole [99]
Magnets don’t need to touch each other in order to be magnetic because all objects have an attraction however, the closer the magnets get, the more magnetic it is.
4 0
3 years ago
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