A distance of d is covered with 53 mile/hr initially.
Time taken to cover this distance t1 = d/53 hour
Next distance of d is covered with x mile hours.
Time taken to cover this distance t2 = d/x hours.
We have average speed = 26.5 mile / hour
= Total distance traveled/ total time taken
= 

1). The little projectile is affected by friction all the way through the block.
Friction robs some kinetic energy.
2). The block is affected by friction as it scrapes along the top of the post.
Friction robs some kinetic energy.
3). The block is also affected by friction with the air (air resistance) as it
falls to the ground. Friction robs some kinetic energy.
Answer:
-4.0 N
Explanation:
Since the force of friction is the only force acting on the box, according to Newton's second law its magnitude must be equal to the product between mass (m) and acceleration (a):
(1)
We can find the mass of the box from its weight: in fact, since the weight is W = 50.0 N, its mass will be

And we can fidn the acceleration by using the formula:

where
v = 0 is the final velocity
u = 1.75 m/s is the initial velocity
t = 2.25 s is the time the box needs to stop
Substituting, we find

(the acceleration is negative since it is opposite to the motion, so it is a deceleration)
Therefore, substituting into eq.(1) we find the force of friction:

Where the negative sign means the direction of the force is opposite to the motion of the box.
Answer: 15m/s
Explanation: <u>Average</u> <u>Velocity</u> is vector describing the total displacement of an object and the time taken to change its position. It is represented as:

At t₁ = 1.0s, displacement x₁ is:

x(1) = 28
At t₂ = 4.0s:

x(4) = 73
Then, average speed is

v = 15
The average velocity of a car between t₁ = 1s and t₂ = 4s is 15m/s
1. If we increase the distance to twice it's original value, the light intensity is reduced by one-fourth, the light intensity would be:
I0/4
2. rms magnetic field is inversely proportional to distance, so the new rms magnetic field would be:
B0/2
3. average energy density is inversely proportional to the square of the distance, so the new average energy density is:
E0/4