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2 years ago

Plsss help I don’t understand this

Physics

2 answers:

nekit [7.7K]2 years ago

6 0

B is the correct option.

1. Given eqn;

S(t) = 1/2t² - 4t + 8

2.Differentiate the above eqn with respect to t;

d(S(t)) = t - 4

When distance, S, is differentiated it results to velocity.

V = t - 4

at t = 10

V = 10 - 4

V = 6 feet/s

mixer [17]2 years ago

4 0

The person above is correct, it’s B

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Answer: the answer is A, C, E

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3 years ago

Starting from rest, a 6.79 kg block slides 2.82 m down a rough 20.7 ◦ incline. The coefficient of kinetic friction between the b

Veronika [31]

Answer:

23.52092 J

Explanation:

m = Mass of block = 6.79 kg

s = Sliding distance = 2.82 m

$\theta$ = Angle of slide = 20.7°

$\mu$ = Coefficient of kinetic friction = 0.425

g = Acceleration due to gravity = 9.8 m/s²

Work done by the force of gravity is given by

$W=mgsin\theta\\\Rightarrow W=6.79\times 9.8\times sin20.7\\\Rightarrow W=23.52092\ J$

The work done by the force of gravity is 23.52092 J

8 0

3 years ago

The table represents the speed of a car in a northern direction over several seconds. Column 1 would be on the x-axis, and Colum

TEA [102]

"The table represents the speed of a car in a northern direction over several seconds. Column 1 would be on the x-axis, and Column 2 would be on the y-axis."

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3 years ago

Read 2 more answers

A piano emits frequencies the range from a low of about 28 Hz to a high of about 4200 Hz. Find the range of wavelengths in air a

Step2247 [10]

V=wave velocity , f= frequency, λ=wavelength 
Use it to find corresponding wavelengths for f=28 Hz 
λ= v/f= 337/28=12.036 m

for f=4200 Hz 
λ= v/f=337/4200= 0.08 m 
So max. wavelength is 12.036 m and 
Min Wavelength is 0.08 m 
So the range is between .08 m and 12.036 m
Hope this helps.

4 0

4 years ago

A 50.0-kg projectile is fired at an angle of 30 degrees above thehorizontal with an initial speed of 1.20 x 102 m/s fromthe top

Advocard [28]

Answer:

a) Em₀ = 42.96 104 J , b) $W_{fr}$ = -2.49 105 J , c) vf = 3.75 m / s

Explanation:

The mechanical energy of a body is the sum of its kinetic energy plus the potential energies it has

Em = K + U

a) Let's look for the initial mechanical energy

Em₀ = K + U

Em₀ = ½ m v2 + mg and

Em₀ = ½ 50.0 (1.20 102) 2 + 50 9.8 142

Em₀ = 36 104 + 6.96 104

Em₀ = 42.96 104 J

b) The work of the friction force is equal to the change in the mechanical energy of the body

$W_{fr}$ = Em₂ -Em₀

Em₂ = K + U

Em₂ = ½ m v₂² + m g y₂

Em₂ = ½ 50 85 2 + 50 9.8 427

Em₂ = 180.625 + 2.09 105

Em₂ = 1,806 105 J

$W_{fr}$ = Em₂ -Em₀

$W_{fr}$ = 1,806 105 - 4,296 105

$W_{fr}$ = -2.49 105 J

The negative sign indicates that the work that force and displacement have opposite directions

c) In this case the work of the friction going up is already calculated in part b and the work of the friction going down would be 1.5 that job

We have that the work of friction is equal to the change of mechanical energy

$W_{fr}$ = ΔEm

$W_{fr}$ = Emf - Emo

-1.5 2.49 10⁵ = ½ m vf² - 42.96 10⁴

½ m vf² = -1.5 2.49 10⁵ + 4.296 10⁵

½ 50.0 vf² = 0.561

vf = √ 0.561 25

vf = 3.75 m / s

6 0

3 years ago