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kumpel [21]
3 years ago
12

A person running down the hallway at a velocity of 4.2 m/s comes to a stop in a time of 1.8 seconds to avoid hitting the wall. W

hat was the acceleration of the person?
A.) 7.6 m/s/s
B.) -7.6 m/s/s
C.) 2.3 m/s/s
D.) -2.3 m/s/s
Physics
2 answers:
kumpel [21]3 years ago
6 0
Hshshshhshdhdhdhdhddhdhdhdhdhdh
adoni [48]3 years ago
3 0

Answer:

It's not -7.6

Explanation:

All I can tell you

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A box slides down a frictionless ramp.if it starts at rest, what is it’s speed at the bottom?
zhenek [66]

8.854 m/s is the speed of the box after it reaches bottom of the ramp.

<u>Explanation</u>:

From the figure we came to know that height of the block is 4 m.

We know that,

Total "initial energy of an object" = Total "final energy of an object "

Total "initial energy of an object" is = "sum of potential energy" and "kinetic energy" of an object at its initial position.

\text { "g" acceleration due to gravity is } 9.8 \mathrm{m} / \mathrm{s}^{2}

\text { Total initial energy }=\mathrm{m} \times \mathrm{g} \times \mathrm{h}_{\mathrm{i}}+\frac{1}{2} \mathrm{m} v_{i}^{2}

Initial velocity is “0” as the object does not have starting speed

\text { Height of the block where the object is placed initially }\left(h_{i}\right) \text { is } 4 \mathrm{m} \text { . }

\text { Total initial energy }=\mathrm{m} \times 9.8 \times 4+\frac{1}{2} \mathrm{m} 0^{2}

Total initial energy = 39.2 × m

\text { Total final energy }=\mathrm{m} \times \mathrm{g} \times \mathrm{h}_{\mathrm{f}}+\frac{1}{2} m v_{f}^{2}

\text { We need to find final velocity } v_f

\text { Height of the block where the object is travelled to bottom (h_) is } 0 \mathrm{m} \text { . }

\text { Total final energy }=\mathrm{m} \times 9.8 \times 0+\frac{1}{2} m v_{f}^{2}

Now,  Total initial energy of an object = Total final energy of an object

39.2 \times \mathrm{m}=0.5 \mathrm{m} v_{f}^{2}

\frac{39.2}{0.5}=v_{f}^{2}

v_{f}^{2}=78.4

v_{f}=\sqrt{78.4}

v_{f}=8.854 \mathrm{m} / \mathrm{s}

Final speed is 8.854 m/s.

3 0
3 years ago
Two forces of magnitudes 4.0 Newtons and 3.0 Newtons pull on a box. The forces make an angle of 40° with each other. What is the
leonid [27]

Answer:

6.6 N

Explanation:

Let's take the direction of the force of 4.0 N as positive x-direction. This means that the force of 3.0 N is at 40 degrees above it. So the components of the two forces along the x- and y-directions are:

F_{1x} = 4.0 N\\F_{1y} = 0

F_{2x} = 3.0 N cos 40^{\circ}=2.3 N\\F_{2y} = 3.0 N sin 40^{\circ} = 1.9 N

So the resultant has components

F_x = F_{1x}+F_{2x}=4.0 N +2.3 N = 6.3 N\\F_y = F_{1y} + F_{2y} = 0 + 1.9 N = 1.9 N

So the magnitude of the resultant is

F=\sqrt{F_x^2 +F_y^2}=\sqrt{(6.3)^2+(1.9)^2}=6.6 N

And in order for the body to be balanced, the third force must be equal and opposite (in direction) to this force: so, the magnitude of the third force must be 6.6 N.

3 0
3 years ago
Help me please. I’ll select brainliest!
pishuonlain [190]

Answer:

90 degrees

Explanation:

the answer is 90 because angle a has a square on the angle which means it is 90 degrees

8 0
3 years ago
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What will change the velocity of a periodic wave?
Gwar [14]
The one that will change the velocity of a periodic wave is : 
B. Changing the medium of the wave
Waves is always determined by the properties of the medium, which means that changing the medium will change the velocity of the wave

hope this helps
7 0
3 years ago
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Firdavs [7]

Answer:

the less shielding of electrons

6 0
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