The force required to slow the truck was -5020 N
Explanation:
First of all, we find the acceleration of the truck, which is given by
where
v is the final velocity
u is the initial velocity
t is the time
For the truck in this problem,
v = 11.5 m/s
u = 21.9 m/s
t = 2.88 s
So the acceleration is
where the negative sign means that this is a deceleration.
Now we can find the force exerted on the truck, which is given by Newton's second law:
where
m = 1390 kg is the mass of the truck
is the acceleration
And substituting,
So the closest answer among the option is -5020 N.
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Answer:
The light ray is reflected back into the opposite direction
Explanation:
The law of reflection states that when a light ray hits a reflecting surface, the angle of reflection (measured between the reflected ray and the normal to the surface) is equal to the angle of incidence (measured between the incident ray and the normal to the surface).
In this case, we have a light ray that it is incident along the normal to the surface: this means that the angle of incidence is . As per the law of reflection, the angle of reflection must be the same: . This means that the reflected ray is also along the normal, just in the opposite direction to that of the incident ray.
Answer:
B: Greatest, A: Second greatest, C: Second geratest.
Explanation:
We can calculate the heat of fusion of a material (ΔHfus), which is the heat required to melt 1 kg of material, using the following expression.
ΔHfus = Q/m
where,
Material A
ΔHfus = 200 J/4 kg = 50 J/kg
Material B
ΔHfus = 300 J/5 kg = 60 J/kg
Material C
ΔHfus = 300 J/6 kg = 50 J/kg
Then, considering the heats of fusion,
B: Greatest, A: Second greatest, C: Second greatest.