A student in Denver (altitude = 1 mile = 1609 m above sea level) brings a physics book of mass 1.3 kg to the top of a ten story
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Answer:
D) momentum of cannon + momentum of projectile= 0
Explanation:
The law of conservation of momentum states that the total momentum of an isolated system is constant.
In this case, the system cannon+projectile can be considered as isolated, because no external forces act on it (in fact, the surface is frictionless, so there is no friction acting on the cannon). Therefore, the total momentum of the two objects (cannon+projectile) must be equal before and after the firing:
But the initial momentum is zero, because at the beginning both the cannon and the projectile are at rest:
So the final momentum, which is sum of the momentum of the cannon and of the projectile, must also be zero:
Answer:
D) The worker will accelerate at 2.17 m/s² and the box will accelerate at 1.08 m/s² , but in opposite directions.
Explanation:
Newton's third law
Newton's third law or principle of action and reaction states that when two interaction bodies appear equal forces and opposite directions. in each of them.
F₁₂= -F₂₁
F₁₂: Force of the box on the worker
F₂₁: Force of the worker on the box
Newton's second law
∑F = m*a
∑F : algebraic sum of the forces in Newton (N)
m : mass in kilograms (kg)
a : acceleration in meters over second square (m/s²)
Formula to calculate the mass (m)
m = W/g
Where:
W : Weight (N)
g : acceleration due to gravity (m/s²)
Data
W₁ =1.8 kN : box weight
W₂ = 0.900 kN : worker weight
F₂₁ = 0.200 kN
F₁₂ = - 0.200 kN
g = 9.8 m/s²
Newton's second law for the box
∑F = m*a
F₂₁ = m₁*a₁ m₁=W₁/g
0.2 kN = (1.8kN)/(9.8 m/s² ) *a₁
a₁= 1.08 m/s² : acceleration of the box
Newton's second law for the worker
∑F = m*a
F₁₂ = m₂*a₂ , m₂=W₂/g
- 0.2 kN =( (0.9 kN) /(9.8 m/s² ) )*a₂
a₂= -2.17 m/s² : acceleration of the worker