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3 years ago

Hi :) I don’t really understand why it’s A

Physics

1 answer:

Troyanec [42]3 years ago

6 0

Answer:

Explanation:

1. When the block moves across a table top, F(pulling) = - F(frictional).

Sum of this forces = 0, so the block moves with uniform speed.

2. When the block is pulled on top of the table covered with beads

F(pulling) > - F(frictional).

So, the sum of forces (∑F) is a number that is more than 0 and directed to the direction of movement.

So, a = ∑F / m is positive and constant. Speed is increasing because

v(t) = v(0)+at

a is constant and directed forward.

That means a is acceleration, and constant.

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A diver leaves the end of a 4.0 m high diving board and strikes the water 1.3s later, 3.0m beyond the end of the board. Consider

shutvik [7]

Answer:

4.0 m/s

Explanation:

The motion of the diver is the motion of a projectile: so we need to find the horizontal and the vertical component of the initial velocity.

Let's consider the horizontal motion first. This motion occurs with constant speed, so the distance covered in a time t is

$d=v_x t$

where here we have

d = 3.0 m is the horizontal distance covered

vx is the horizontal velocity

t = 1.3 s is the duration of the fall

Solving for vx,

$v_x = \frac{d}{t}=\frac{3.0 m}{1.3 s}=2.3 m/s$

Now let's consider the vertical motion: this is an accelerated motion with constant acceleration g=9.8 m/s^2 towards the ground. The vertical position at time t is given by

$y(t) = h + v_y t - \frac{1}{2}gt^2$

where

h = 4.0 m is the initial height

vy is the initial vertical velocity

We know that at t = 1.3 s, the vertical position is zero: y = 0. Substituting these numbers, we can find vy

$0=h+v_y t - \frac{1}{2}gt^2\\v_y = \frac{0.5gt^2-h}{t}=\frac{0.5(9.8 m/s^2)(1.3 s)^2-4.0 m}{1.3 s}=3.3 m/s$

So now we can find the magnitude of the initial velocity:

$v=\sqrt{v_x^2+v_y^2}=\sqrt{(2.3 m/s)^2+(3.3 m/s)^2}=4.0 m/s$

4 0

3 years ago

Which activity would be the best choice foir a lifelong fitness program

Fantom [35]

I think jogging/running/walking because you don't need any equipment and you can structure around it on your own time.

7 0

2 years ago

Read 2 more answers

Explain how VSEPR theory predicts the shapes of molecules. Match the words in the left column to the appropriate blanks in the s

vlabodo [156]

Answer:

The VSEPR theory and how it predicts the shapes of molecules:

Explanation:

The Valence Shell Electron Pair Repulsion (VSEPR) theory is a model used in chemistry to predict the shapes of individual molecules by the number of electron pairs that they have in the center of the atom. This theory is also based on the notion that the electrons around the atom repel one another. The Valence electrons on the outermost layer of the molecule are the most important in defining the geometry as they are the first to interact with other atoms and will be involved in bonding.

8 0

3 years ago

Consider the data collected in science class. Different masses were thrown with varied amounts of

lesya [120]

Answer:

A: In all cases, the acceleration was the same.

Explanation:

I know this because its a clear obvious answer not only that it was one of my USA TESTPREP questions and it was right.

All you mainly have to do is the math - F=ma , In each case , the acceleration is 5 m/s squared

4 0

3 years ago

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Two 2 kg masses is placed at either end of a rod that has a mass of .5 kg and a length of 3 m. What is the moment of inertia if

sergij07 [2.7K]

Explanation:

a) $I=\displaystyle \sum_{i}m_ir_i^2$

where $r_i$ is the distance of the mass $m_i$ from the axis of rotation. When the axis of rotation is placed at the end of the rod, the moment of inertia is due only to one mass. Therefore,

$I= mr^2 = (2\:kg)(3\:m)^2 = 18\:kg-m^2$

b) When the axis of rotation is placed on the center of the rod, the moment is due to both masses and the radius r is 1.5 m. Therefore,

$\displaystyle I= \sum_{i}m_ir_i^2 = 2(2\:kg)(1.5\:m)^2 = 9\:kg-m^2$

7 0

2 years ago