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.
Assuming that all the bullet’s energy heats the paraffin, its final temperature is 27.1 degree C. The correct option is D.
<h3>What is temperature?</h3>
Temperature is the degree of hotness and coldness of the material.
The energy of the bullet E = 1/2 mv²
E = 1/2 x 10 x 10⁻³ x (2000)²
E = 2 x 10⁴ J
This heat is used in heating the paraffin
E = m x c ΔT = m x c (Tfinal -Tinitial)
2 x 10⁴ J = 1 x 2.8 x 10³ x (Tfinal -20)
Tfinal = 27.1°C
Thus, the final temperature is 27.1 degree C. The correct option is D.
Learn more about temperature.
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This question involves the concepts of th magnetic field and current.
The magnetic field created by the current at the house is "6.75 x 10⁻⁷ T".
<h3>Magnetic Field</h3>
The magnetic field created by a current carrying wire can be given by the following formula:
where,
- B = magnetic field = ?
= permeabiliy of free space =4π x 10⁻⁷- I = current = 152 A
- r = distance = 45 m
B = 6.75 x 10⁻⁷ T
Learn more about magnetic field here:
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Answer: Yes, he is exceeding the speed limit
Explanation:
Hi!
This is problem about unit conversion
1 mile = 1,609.344 m
Then the speed limit v is:
v = 75 mi/h = 120,700.8 m/h
1 hour = 60 min = 60*60 s = 3,600 s
v = (120,700.8/3,600) m/s = 33.52 m/s
38 m/s is higher than the speed limit v.
Answer:
Halley's comet will next appear in the night sky in the year 2062. It orbits the sun every 75-76 years, so this is the time between appearances.
