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3 years ago

Which two of the following are the least dense materials shown?

Physics

2 answers:

sergiy2304 [10]3 years ago

7 0

I did this test, i think its loaf of bread and pillow

uysha [10]3 years ago

3 0

Pillow. When you make the mass of off substances equivalent, the pillow takes up the most volume. This means it is the least dense.

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in the derivation of the time period of a pendulum in electric field when considering the fbd of bob to find the g effective why

Neko [114]

Answer:

we learned that an object that is vibrating is acted upon by a restoring force. The restoring force causes the vibrating object to slow down as it moves away from the equilibrium position and to speed up as it approaches the equilibrium position. It is this restoring force that is responsible for the vibration. So what forces act upon a pendulum bob? And what is the restoring force for a pendulum? There are two dominant forces acting upon a pendulum bob at all times during the course of its motion. There is the force of gravity that acts downward upon the bob. It results from the Earth's mass attracting the mass of the bob. And there is a tension force acting upward and towards the pivot point of the pendulum. The tension force results from the string pulling upon the bob of the pendulum. In our discussion, we will ignore the influence of air resistance - a third force that always opposes the motion of the bob as it swings to and fro. The air resistance force is relatively weak compared to the two dominant forces.

The gravity force is highly predictable; it is always in the same direction (down) and always of the same magnitude - mass*9.8 N/kg. The tension force is considerably less predictable. Both its direction and its magnitude change as the bob swings to and fro. The direction of the tension force is always towards the pivot point. So as the bob swings to the left of its equilibrium position, the tension force is at an angle - directed upwards and to the right. And as the bob swings to the right of its equilibrium position, the tension is directed upwards and to the left. The diagram below depicts the direction of these two forces at five different positions over the course of the pendulum's path.

that's what I know so far

8 0

3 years ago

6. Rock Ais thrown horizontally off a cliff with a velocity of 15 m/s. The rock lands 75m from

Harman [31]

Answer:

5 seconds

Explanation:

3 0

3 years ago

What is the power of a student that has done a work of 10 joules in 10 seconds

Alla [95]

Answer:

1 Watt

Explanation:

P=W/t

P=10/10

P=1 Watt

8 0

3 years ago

Which figure represents the electric field lines of two positive point charges?

Naddik [55]

Electric field lines of positive charges are always radially outwards

So here all field lines must have tendency to move out radially as well as two field lines never intersects with each other

So here field lines also do not intersects with each other

So overall the figure C is perfectly representing the field lines of two positive charges as these lines are not intersecting and also originating from two positive charges.

So answer must be

<u><em>FIGURE C</em></u>

7 0

3 years ago

A tennis player tosses a tennis ball straight up and then catches it after 1.25 s at the same height as the point of release.

Alenkasestr [34]

Answer:

A. 9.8 m/s²

B. Zero

C. 6.125 m/s

D. 1.91 m

Explanation:

From the question given above, the following data were obtained:

Time (T) spent in the air = 1.25 s

A. Determination of the acceleration of the ball.

From the description given in question above, the motion of the tennis ball is motion under gravity. Hence, the ball will experience an acceleration due to gravity of 9.8 m/s²

B. Determination of the velocity at maximum height.

Maximum height is the greatest point reached by the tennis ball above the ground. At maximum height, the velocity of the tennis ball is zero since it has no further force to propel it upward.

C. Determination of the initial velocity of the ball.

We'll begin by calculating the time taken to reach the maximum height. This can be obtained as follow:

Time (T) spent in the air = 1.25 s

Time (t) to reach the maximum height =?

T = 2t

1.25 = 2t

Divide both side by 2

t = 1.25 / 2

t = 0.625 s

Finally, we shall determine the initial velocity of the ball. This can be obtained as follow:

Time (t) to reach the maximum height = 0.625 s

Acceleration due to gravity (g) = 9.8 m/s²

Final velocity (v) = 0 (at maximum height)

Initial velocity (u) =?

v = u – gt (since the ball is going against gravity)

0 = u – (9.8 × 0.625)

0 = u – 6.125

Collect like terms

0 + 6.125 = u

u = 6.125 m/s

Thus, the initial velocity of the ball is 6.125 m/s

D. Determination of the maximum height.

Acceleration due to gravity (g) = 9.8 m/s²

Final velocity (v) = 0 (at maximum height)

Initial velocity (u) = 6.125 m/s

Maximum height (h) =?

v² = u² – 2gh (since the ball is going against gravity)

0² = 6.125² – (2 × 9.8 × h)

0 = 37.52 – 19.6h

Collect like terms

0 – 37.52 = – 19.6h

– 37.52 = – 19.6h

Divide both side by – 19.6

h = – 37.52 / – 19.6

h = 1.91 m

Thus, the maximum height reached by the ball is 1.91 m

3 0

3 years ago