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3 years ago

Please help !!

1 answer:

3 0

If the speed is constant, the acceleration a must be zero. Since force F = m•a, the total force must be zero.
In a 1D case, work W is the product of force F and distance d: W = F • d.
Since there is no more information given about friction or air resistance, I have to assume you are looking for the work done by the total force, wich is also zero.

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two people, each with a mass of 70 kg, are wearing inline skates and are holding opposite ends of a 15m rope. One person pulls f

Zina [86]

Answer:

7.75 s

Explanation:

Newton's second law:

∑F = ma

35 N = (70 kg) a

a = 0.5 m/s²

Given v₀ = 0 m/s and Δx = 15 m:

Δx = v₀ t + ½ at²

(15 m) = (0 m/s) t + ½ (0.5 m/s²) t²

t = 7.75 s

5 0

3 years ago

An astronaut drops a hammer from 2.0 meters above the surface of the Moon. If the acceleration due to gravity on the Moon is 1.6

Elenna [48]

Answer:

option C

Explanation:

given,

height of the hammer, h = 2 m

acceleration due to gravity of the moon, g = 1.62 m/s²

time taken by the hammer to reach at bottom = ?

initial speed of the hammer, u = 0 m/s

using equation of motion for the time calculation

$s = ut + \dfrac{1}{2}gt^2$

$2 = 0+\dfrac{1}{2}\times 1.62\times t^2$

t² = 2.469

t = 1.57 s ≅ 1.6 s

hence, the time taken by the hammer to reach the bottom is equal to 1.6 s.

The correct answer is option C

8 0

4 years ago

a. A beam of light is incident from air on the surface of a liquid. If the angle of incidence is 26.7° and the angle of refracti

Diano4ka-milaya [45]

Answer:

(a). The critical angle for the liquid when surrounded by air is 44.37°

(b). The angle of refraction is 26.17°.

Explanation:

Given that,

Incidence angle = 26.7°

Refraction angle = 18.3°

(a). We need to calculate the refraction of liquid

Using Snell's law

$n=\dfrac{\sin i}{\sin r}$

Put the value into the formula

$n=\dfrac{\sin 26.7}{\sin 18.3}$

$n=1.43$

We need to critical angle for the liquid when surrounded by air

Using formula of critical angle

$C=\sin^{-1}(\dfrac{1}{n})$

Put the value into the formula

$C=\sin^{-1}(\dfrac{1}{1.43})$

$C=44.37^{\circ}$

(b). Given that,

Incidence angle = 37.5°

Speed of light in mineral $v=2.17\times10^{8}\ m/s$

We need to calculate the index of refraction

Using formula of index of refraction

$n=\dfrac{c}{v}$

Put the value into the formula

$n=\dfrac{3\times10^{8}}{2.17\times10^{8}}$

$n=1.38$

We need to calculate the angle of refraction

Using Snell's law

$n=\dfrac{\sin i}{\sin r}$

$\sin r=\dfrac{\sin i}{n}$

Put the value into the formula

$\sin r=\dfrac{\sin 37.5}{1.38}$

$r=\sin^{-1}(\dfrac{\sin 37.5}{1.38})$

$r=26.17^{\circ}$

Hence, (a). The critical angle for the liquid when surrounded by air is 44.37°

(b). The angle of refraction is 26.17°.

3 0

3 years ago

Read 2 more answers

Energy of a SpacecraftVery far from earth(at R=\infty), a spacecraft has run out of fuel and its kineticenergy is zero. If only

Firdavs [7]

Answer:

$s_e=\sqrt{\frac{2GM_e}{R_e^2}}$

Explanation:

In this case mechanical energy is conserved, which means that the sum of the initial kinetic energy and initial potential gravitational energy will be equal to the sum of the final kinetic energy and final potential gravitational energy:

$K_i+U_i=K_f+U_f$