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zysi [14]
2 years ago
8

When you come within 100 ft of the uncontrolled railroad crossing and you cannot see the tracks for 400 ft in both directions, t

he speed limit is ____ mph?
Physics
1 answer:
Sergio039 [100]2 years ago
6 0
The answer to the blank above is 20. The speed limit given provided that you cannot see the tracks for 400 ft in both directions is always 20 mph. Basically, this 20 mph is decided based upon the traffic laws in order to avoid road casualties. Since it is "uncontrolled railroad crossing", the minimum speed should be implemented to slow down for the purpose of traffic calming measures. Other than this, the 20 mph is also applicable in narrowing roads as well as speed humps.
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A car is traveling with speed v0 when it begins to speed up at a rate of Δv every second. After t1 seconds, the car travels with
Rainbow [258]

Answer:

d = Δv(t2-t1)

Explanation:

Speed is defined as the change of displacement with respect to time. It is expressed as shown;

Speed = change in displacement/change in time

Δv = d/Δt

d = Δv*Δt

d = ΔvΔt

Δt = t2-t1

d = Δv(t2-t1)

Δv is the change in rate of speed

Δt = change in time

The correct expression for the displacement of the car during this motion is d = Δv(t2-t1)

8 0
2 years ago
Identify the row that contains two scalars and one vector quantity: Distance Acceleration Velocity Speed Mass Acceleration Dista
GenaCL600 [577]

Answer:

Speed, mass and acceleration

Explanation:

A scalar quantity is a quantity that has only magnitude but no direction while a vector quantity has both magnitude and direction.

According to the question, the row that has two scalars and one vector is speed, mass and acceleration.

The two scalars in this row are speed and mass while the vector quantity there is the acceleration.

Acceleration has direction since it possess direction. A body accelerating will do so in a particular direction. Speed and mass doesn't possess any direction. Mass only specify the magnitude of the body but no clue as to which direction is the body moving towards.

Speed also only specify the

total distance covered with respect to time but not the direction of the direction.

8 0
2 years ago
Three identical 50-kg balls are held at the corners of an equilateral triangle, 30 cm on each side. if one of the balls is relea
natima [27]
F1 = G*m²/D² 
<span>F = 2*F1*cos30° = 2*G*50²*cos30°/0.3² = 3.21E-6 </span>

<span>a = F/m = 3.21E-6/50 = 6.42E-8

Hope this helped!
STSN</span>
3 0
2 years ago
Read 2 more answers
The researcher requires the force on the wire to point upward with a magnitude of 4.2x10-4 N. The length of the wire that is in
lorasvet [3.4K]

Answer:

The magnetic force can be found by using the following equation:

F_B = IL\times B

Let’s first deal with the magnitude, then we will figure out the direction by using the right hand rule.

4.2\times 10^{-4} = (30\times 10^{-3})\times  (50\times10^{-3}) \times B\\4.2 \times 10^{-4} = 1500 \times 10^{-6}\times B\\(28\times 10^{-4})\times 10^2 = B\\B = 28\times 10^{-2}

The direction of the L is equal to the direction of the current. So, the direction of the L is to the right. The required force is to be pointed upward.

By the right hand rule the magnetic field should be directed towards ‘into the plane’.

Explanation:

In the questions regarding the magnetic field, the cross product and the directions of the vectors are crucial. So, you should use right-hand rule efficiently.

Right-hand rule: A \times B = C

Point your four fingers (except the thumb) towards the same direction as A.

Point your palm towards the same direction as B.

Your thumb should show the direction of C.

5 0
2 years ago
A water-skier with weight Fg = mg moves to the right with acceleration a. A horizontal tension force T is exerted on the skier b
Degger [83]

Answer:

The correct relationships are T-fg=ma and L-fg=0.

(A) and (C) is correct option.

Explanation:

Given that,

Weight Fg = mg

Acceleration = a

Tension = T

Drag force = Fa

Vertical force = L

We need to find the correct relationships

Using balance equation

In horizontally,

The acceleration is a

T-Fd=ma...(I)

In vertically,

No acceleration

w=L

mg-L=0

Put the value of mg

L-fg=0....(II)

Hence,  The correct relationships are T-fg=ma and L-fg=0.

(A) and (C) is correct option.

3 0
2 years ago
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