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3 years ago

A car traveling at 15 m/s starts to decelerate steadily. It comes to a complete stop in 5 seconds. What is its acceleration ?

Physics

1 answer:

Nataliya [291]3 years ago

5 0

Answer:

$-3m {s}^{-2}$

Explanation:

The initial velocity, u, of the car=15m/s

The final velocity, v, of the car =0m/s

Time, t, taken for the car to come to a stop=5s

Acceleration is calculated by,

$a= \frac{v - u}{t}$

By substitution,

$a= \frac{0- 15}{5}$

$a= \frac{- 15}{5}$

$a = -3 {ms}^{ - 2}$

The negative sign implies that the car has decelerated.

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A student rides a bicycle for 15 miles in 3 hours. What is the student's speed? What else would you need to know for the velocit

kaheart [24]

Answer:

5 miles per hour

Explanation:

if you divide 15 by 3 you get 5, therefore the student is going 5 miles per hour.

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2 years ago

3. If a car is moving at 90km/hr and it rounds a corner, also at 90km/hr. Does it maintain

dolphi86 [110]

Answer:

Constant speed: yes

Constant velocity: no

Explanation:

Let's remind the definition of speed and velocity:

- Speed is a scalar quantity, which is equal to the ratio between the distance covered (regardless of the direction) and the time taken:

$s=\frac{d}{t}$

- Velocity is a vector quantity, so it has both a magnitude and a direction. The magnitude is equal to the rate between the displacement of the object and the time taken, while the direction is the same as the displacement.

In this problem, we notice that:

- The speed of the car remains constant, as it is 90 km/h

- However, its direction of motion changes while the car travels round the corner: this means that the direction of the velocity is also changing, therefore velocity is not constant.

8 0

3 years ago

A parallel beam of light in air makes an angle of 43.5 ∘ with the surface of a glass plate having a refractive index of 1.68. Yo

aniked [119]

Answer:

a) 46.5º b) 64.4º

Explanation:

To solve this problem we will use the laws of geometric optics

a) For this part we will use the law of reflection that states that the reflected and incident angle are equal

θ = 43.5º

This angle measured from the surface is

θ_r = 90 -43.5

θ_s = 46.5º

b) In this part the law of refraction must be used

n₁ sin θ₁ = n₂. Sin θ₂

sin θ₂ = n₁ / n₂ sin θ₁

The index of air refraction is n₁ = 1

The angle is this equation is measured between the vertical line called normal, if the angles are measured with respect to the surface

θ_s = 90 - θ

θ_s = 90- 43.5

θ_s = 46.5º

sin θ₂ = 1 / 1.68 sin 46.5

sin θ₂ = 0.4318

θ₂ = 25.6º

The angle with respect to the surface is

θ₂_s = 90 - 25.6

θ₂_s = 64.4º

measured in the fourth quadrant

3 0

3 years ago

What’s the velocity of a ball falling with 100 joules of kinetic energy and a mass of 2 kilograms

ohaa [14]

Answer:

the velocity is 10 m/s

Explanation:

Using the expression for kinetic energy we have:

$Ek=\frac{1}{2} *m*v^{2} \\\\Ek=100J\\m=2kg\\v=\sqrt{(2*100/2)}\\ v=10[m/s]$

3 0

3 years ago

The wavelength of light that has a frequency of 1.20 × 1013 s-1 is ________ m.

klio [65]

The relationship between frequency and wavelength for an electromagnetic wave is
$c=f \lambda$
where
f is the frequency
$\lambda$ is the wavelength
$c=3 \cdot 10^8 m/s$ is the speed of light.

For the light in our problem, the frequency is $f=1.20 \cdot 10^{13} s^{-1}$ , so its wavelength is (re-arranging the previous formula)
$\lambda= \frac{c}{f}= \frac{3 \cdot 10^8 m/s}{1.20 \cdot 10^{13} s^{-1}}= 2.5 \cdot 10^{-5}m$

8 0

3 years ago