Ask question

Ask question

All categories

3 years ago

10

A person wearing rollerblades starts from rest and accelerates at a constant rate. She reaches a speed of 13 mph (5.18 m/s) exac

tly 18.0 s later.
a. What is the magnitude of their average acceleration (in m/s2)?
b. How far does the person on rollerblades travel in that period of time?

2 answers:

Vinil7 [7]3 years ago

8 0

Answer:
a. Acceleration = 0.28 m/s^2
b. Distance = 45.36 m

Explanation:

kvv77 [185]3 years ago

5 0

Answer: a. ) What is the magnitude of their average acceleration (in m/s2)

You might be interested in

A dripping water faucet steadily releases drops 1.0 s apart. As these drops fall, does the distance between them increase, decre

ololo11 [35]

Answer:

Distance between them increase

Explanation:

The position S of the water droplet can be determined using equation of motion

$S=ut+\frac{1}{2} at^2$

where $u$ is the initial velocity which is zero here

$t$ is time taken, $a$ is acceleration due to gravity

the position of first drop after time $t$ is given by

$S_{1} =0 \times t+ \frac{1}{2} at^2=\frac{1}{2} at^2............(1)$

the position of next drop at same time is

$S_{2} =\frac{1}{2} a(t-1)^2 = \frac{1}{2} a(t^2+1-2t)............(2)$

distance between them is $S_{1} -S_{2}$ is $a(t-1)$

from the above the difference will increase with the time

3 0

3 years ago

One block rests upon a horizontal surface. A second identical block rests upon the first one. The coefficient of static friction

goblinko [34]

Answer:

The magnitud of the force is 124.8N.

Explanation:

First we have to find the value of the static friction coefficient, when the external force F is applied to upper block (i will call it A Block) we have a free body diagram as the one shown in the figure i attached, so since this block has no aceleration in any direction the force F should be equal to the friction force between A and B block, one we noticed this we can use the equation for the Friction force to find the coefficient:

$0=F-FrictionAB$

$F=FrictionAB=Nab*$ μs

and again, since the block has no acceleration the normal between A and B block should be equal to the weigth of the first block, so we have:

$0=Nab-W$

$Nab=W=mg$

replacing this we have:

$F=$ μs $*Nab=$ μs* $mg=41.6N$

and μs $=41.6N/(mg)$

now it's time to see the free body diagram for the b block, if we now apply the F force to the B block the diagram should look like in the figure.

the color of the arrow gives you an idea of where the force comes from, the blue ones comes from the B block, the red ones from the A block and the brown ones from the ground.

now for the B block you can see two friction forces, one for the ground and one for the A block, both of these directed bacwards, and two normal forces, again one for the ground and one for the A block but the normal force for the A block is aiming downwards.

again we use the fact that the block is not accelerating in any direction so the sum of the forces in x and y direction have to be 0, so:

$F-Friction1(ground)-Friction2(AB)=0$

This is the new external F force that we are looking for:

$F=Friction1(ground)+Friction2(AB)$

we know Friction2(AB) because we found that in the previous block so:

$F=Friction1(ground)+mg$ *μs

for the other friction we have to use the equation:

$Friction(ground)=N(ground)$ *μs

from y axis we have:

$N(ground)-w-Normal(AB)=0$

$N(ground)=w+Normal(AB)$

we found the value of Normal(AB) with the previous block so:

$N(ground)=mg+mg=2mg$

and:

$Friction(ground)=2mg$ *μs

$F=Friction(ground)+mg$ *μs

$F=2mg$ *μs+μs* $mg=3mg$ *μs

and since: μs* $mg=41.6N$

the new F force would be:

$F=3mg$ *μs $=41.6*3=124.8N$

4 0

3 years ago

If a driver is tired, the thinking distance will be less. True or false.why?

Evgesh-ka [11]

Answer:

False

Explanation:

When a driver is impaired the brain will need an extra second or two to wake up, after it does wake up it tends to drift off regularly.

8 0

3 years ago

Diego hypothesizes that the Earth wobbles on its axis in a pattern that is repeated every 20,000 years.

DedPeter [7]

Answer:

D. make a model

Explanation:

3 0

3 years ago

a conical pendulum is formed by attaching a 50g mass to a 1.2m string. The mass swings around the circle of radius 25cm (a) calc

kipiarov [429]

A. 0.5 miles an hour
B. 0.2 miles an hour

4 0

3 years ago