50 POINTS ANSWER CORRECTLY

.Which of the following scenarios correctly describes Newton's First Law?

hodyreva [135]

Answer:

A chair that for some reason won't move even after being pushed.

Explanation:

Newton's first law states that, if a body is at rest or moving at a constant speed in a straight line, it will remain at rest or keep moving in a straight line at constant speed unless it is acted upon by a force. This postulate is known as the law of inertia.

Hope this helps! Sorry if I'm wrong.

7 0

3 years ago

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An electron moving with a speed of 4.0 * 105 m>s in the positive x direction experiences zero magnetic force. When it moves i

IgorLugansk [536]

Answer:

Explanation:

Given that,

Charge on an electron is

q=1.609×10^-19C

Speed of electron V=4×10^5 m/s in positive x direction

V = 4×10^5 •i m/s

At this point F=0N

When the electron is moving in positive y direction

V =4×10^5 •j m/s

F = 3.2×10^-13 N in positive z direction.

F = 3.2×10 ^-13 •k N

What is the direction and magnitude of the magnetic field B?

The force in a magnetic field is given as

F = q (V ×B)

The only time V×B is zero is when both V and B are in same direction

This shows that B is in the positive x direction or negative x direction

i.e B= Bx •i

Now applying this to the second condition

F= q(V×B)

3.2×10^-13 •k =1.609×10^-19 × (4×10^5•j ×Bx •i)

Note that, j×i =-k

3.2×10^-13 •k / 1.609×10^-19 = (4×10^5Bx •(j×i))

1988812.927 •k =- 4×10^5Bx•k

1988812.927/4×10^5 •k =-Bx •k

4.972 •k =-Bx •k

Then, Bx = -4.972 •k Telsa

Then, the magnitude of B is

B=4.972 T

And its direction is negative z direction.

4 0

3 years ago

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If block D weighs 300 lb and block B weighs 275 lb determine the required weight of block C and the angle theta for equilibrium?

adoni [48]

Set up a free body diagram.

and by reason, Tcd = Tbd 

Tbd y = 275 - 300*sinθ 
Tcd y = Tc - 300*sin30 

Tbd x = 300*cosθ 
Tcdx = 300 * cos30 

Tbd^2 = (275 - 300*sinθ)^2 + (300*cosθ)^2 
Tcd^2 = (300*sin30)^2 + (300 * cos30)^2 

(275 - 300*sinθ)^2 + (300*cosθ)^2 = (300*sin30)^2 + (300 * cos30)^2 
etc.

5 0

3 years ago

Sam, whose mass is 78 kg , stands at the top of a 11-m-high, 110-m-long snow-covered slope. His skis have a coefficient of kinet

Valentin [98]

Answer:

v = 8.09 m/s

Explanation:

For this exercise we use that the work done by the friction force plus the potential energy equals the change in the body's energy.

Let's calculate the energy

starting point. Higher

Em₀ = U = m gh

final point. To go down the slope