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asambeis [7]
3 years ago
8

A pencil is rolled off a table of height 0.92 m. If it has horizontal speed pf 1.4 m/s, how long does it take the pencil to reac

h the ground?
Physics
1 answer:
Alenkasestr [34]3 years ago
3 0

The distance an object falls, from rest, in gravity is

                         D  =  (1/2) (G) (T²)

                        'T' is the number seconds it falls.

In this problem,

                         0.92 meter = (1/2) (9.8) (T²)

Divide each side by  4.9 :   0.92 / 4.9 = T²

Take the square root
of each side:                          √(0.92/4.9) = T

                                                  0.433 sec = T    

The horizontal speed doesn't make a bit of difference in
how long it takes to reach the floor.  BUT ... if you want to
know how far from the table the pencil lands, you can find
that with the horizontal speed.

The pencil is in the air for  0.433 second.
In that time, it travels
                                   (0.433s) x (1.4 m/s) = 0.606 meter

from the edge of the table.
 
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On a spinning ride at the fair, it is inertia that keeps you moving in a circle. true or false​
lions [1.4K]

False, the inertia does not keep us moving in a circle on a spinning ride at the fair.

Answer: Option B

<u>Explanation: </u>

Inertia is the resisting force of any object which resists in change in their state. If an object is moving the inertia will act in opposing direction to the force acting on the object stopping its motion.

Similarly, if an object resembles at rest, then the inertia will be acting against the force tending to move that stationary object. So, on a spinning ride at fair, when a person sits there, the inertia acting on the person will prevent the person to falling down from the fair and not in moving in a circle.

6 0
3 years ago
Bob walks 370 m south, then jogs 410 m southwest, then walks 370 m in a direction 28 degrees east of north.
wlad13 [49]
We will measure all angles from West, the negative x-axis and divide the journey into 3 parts:
P1 = 370y
P2 = 410cos(45)x + 410sin(45)y = 290x + 290y
P3 = 370cos(270 - 28)x + 370sin(270 - 28) = -174x - 327y

Overall displacement:
x = 290 - 174 = 116 m
y = 370 + 290 - 327 = 333 m

displacement = √(116² + 333²)
= 353 m

Direction:
tan(∅) = y/x
∅ = tan⁻¹ (333 / 116)
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5 0
3 years ago
Read 2 more answers
(a) what will an object weigh on the moon's surface if it weighs 100 n on earth's surface
juin [17]
We know the equation

weight = mass × gravity

To work out the weight on the moon, we will need its mass, and the gravitational field strength of the moon.
Remember that your weight can change, but mass stays constant.

So using the information given about the earth weight, we can find the mass by substituting 100N for weight, and we know the gravity on earth is 10Nm*2 (Use the gravitational field strength provided by your school, I am assuming yours in 10Nm*2)

Therefore,

100N = mass × 10
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Now, all we need are the moon's gravitational field strength and to apply this to the equation

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4 0
3 years ago
The platform height for Olympic divers is 10 m. A 60 kg diver steps off the platform to begin his dive.
azamat

Answer:

a) Ep = 5886[J]; b) v = 14[m/s]; c)   W = 5886[J]; d) F = 1763.4[N]

Explanation:

a)

The potential energy can be found using the following expression, we will take the ground level as the reference point where the potential energy is equal to zero.

E_{p} =m*g*h\\where:\\m = mass = 60[kg]\\g = gravity = 9.81[m/s^2]\\h = elevation = 10 [m]\\E_{p}=60*9.81*10\\E_{p}=5886[J]

b)

Since energy is conserved, that is, potential energy is transformed into kinetic energy, the moment the harpsichord touches water, all potential energy is transformed into kinetic energy.

E_{p} = E_{k} \\5886 =0.5*m*v^{2} \\v = \sqrt{\frac{5886}{0.5*60} }\\v = 14[m/s]

c)

The work is equal to

W = 5886 [J]

d)

We need to use the following equation and find the deceleration of the diver at the moment when he stops his velocity is zero.

v_{f} ^{2}= v_{o} ^{2}-2*a*d\\where:\\d = 2.5[m]\\v_{f}=0\\v_{o} =14[m/s]\\Therefore\\a = \frac{14^{2} }{2*2.5} \\a = 39.2[m/s^2]

By performing a sum of forces equal to the product of mass by acceleration (newton's second law), we can find the force that acts to reduce the speed of the diver to zero.

m*g - F = m*a

F = m*a - m*g

F = (60*39.2) - (60*9.81)

F = 1763.4 [N]

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