Will give brainlist!

A car whose initial speed is 30 m/s slows uniformly to 10 m/s in 5 seconds. Determine the acceleration of the car. Sketch a gra

Anton [14]

Initial velocity=u=30m/s
Final velocity=v=10m/s
Time=5s

$\\ \sf\longmapsto Acceleration=\dfrac{v-u}{t}$

$\\ \sf\longmapsto Acceleration=\dfrac{10-30}{5}$

$\\ \sf\longmapsto Acceleration=\dfrac{-20}{5}$

$\\ \sf\longmapsto Acceleration=-4m/s^2$

Now

For the second question

Time=3s

Using 2nd equation of motion

$\\ \sf\longmapsto s=ut+\dfrac{1}{2}at^2$

$\\ \sf\longmapsto s=30(3)+\dfrac{1}{2}(-4)(3)^2$

$\\ \sf\longmapsto s=90-2(9)$

$\\ \sf\longmapsto s=90-18$

$\\ \sf\longmapsto s=72m$

5 0

3 years ago

Steven carefully places a 1.65-kg wooden block on a frictionless ramp, so that the block begins to slide down the ramp from rest

nadya68 [22]

Answer:

a. Gravity and c. Spring

Explanation:

Formula for work energy $W = \vec{F} \bullet \vec{S} = FScos(\alpha)$

whereas F is the force acting on the block, S is the distance traveled, and $\alpha$ is the angle between 2 vectors F and S.

If F is perpendicular to S, then

$\alpha = 90^o$

$cos(\alpha) = cos(90^o) = 0$

$W = FS*0 = 0$

a. Normal force is the reaction force acting from the ramp back on the wooden block. This force is perpendicular to the direction of sliding. Therefore this force would do no work.

b. Gravity is the force acting downward, this would have an angle of $90^o - 58.3^o = 31.7^o$ degrees so the work is non-zero.

c. Spring force would have the same direction as sliding so the work is non-zero.

d. Friction force would have the same direction as sliding. However, as this is a frictionless ramp, the friction coefficient would be 0. Friction force would also be zero and so as its work.

5 0

4 years ago

Light passes from a material A, which has an index of refraction of 4/3, into material B, which has an index of refraction of 5/

katrin2010 [14]

Answer:

(b) 32.2°

Explanation:

Using Snell's law as:

$n_i\times {sin\theta_i}={n_r}\times{sin\theta_r}$

Where,

${\theta_i}$ is the angle of incidence ( 30.0° )

${\theta_r}$ is the angle of refraction ( ? )

${n_r}$ is the refractive index of the refraction medium (Material B, n=5 / 4)

${n_i}$ is the refractive index of the incidence medium (Material A, n=4 / 3)

Hence,

${\frac {4}{3}}\times {sin30.0^0}={\frac {5}{4}}\times{sin\theta_r}$

Angle of refraction = $sin^{-1}0.5333$ = 32.2°

5 0

4 years ago

Can someone help? Thanks.

Lilit [14]

The average speed of Frank's car is 2 m/s and the average speed of Noah's car is 1.8 m/s.

<u>Explanation:</u>

Average speed is the measure of total distance covered at different time period. Since, the formula used for calculating the average speed is the ratio of total distance covered by each car to the time taken to cover that distance.

As there is only one set of data i.e., distance and time, the average speed will be equal to the speed of the car.

So in this case, the total distance covered by franks car is 300 cm = 3 m in 1.5 s. Then, the average speed will be

$Avg. S_{frank} = \frac{Total\ distance\ rolled\ by\ his\ car}{Time\ taken}$

$Avg.S_{frank} =\frac{300 \times 10^{-2} }{1.5}=2\ m/s$

Similarly, the average speed of Noahs car which rolled a distance of 360 cm = 3.6 m in time 2 s, will be

$Avg.S_{Noah} =\frac{360 \times 10^{-2} }{2}=1.8\ m/s$

Thus, the average speed of Frank's car is 2 m/s and the average speed of Noah's car is 1.8 m/s.

4 0

4 years ago

A fly wheel with a diameter of 1.20m is rotating at an angular speed of 200 Rev/min

gladu [14]

Answer:a) 20.944rad/s (b) 12.57m/s (c) 800rev/min²

Explanation:

5 0

3 years ago