Answer:
B) A car slowing as it reaches a traffic light.
Explanation:
Newton's second law states that an object which experiences unbalanced forces has an acceleration, according to the equation:
where
F is the net force acting on the object
m is its mass
a is its acceleration
When the forces are unbalanced, it means that the net force F is different from zero, so the acceleration of the object (a) is also different from zero.
Now let's analyze each situation:
A) A box resting on a horizontal floor. --> The object is at rest, so it is not accelerating. This means that the forces acting on it are balanced (net force = 0), so this is not the correct choice
B) A car slowing as it reaches a traffic light. --> The car is slowing down, this means that it has an acceleration: therefore, it is experiencing unbalanced forces. So, this is the correct choice.
C) A car with its cruise control set to 30 km/h. --> The car is moving at constant velocity, so it has zero acceleration. This means that the forces acting on it are balanced (net force = 0), so this is not the correct choice
D) A penny at terminal velocity after falling off of a building. --> The penny is at terminal velocity, which means that it is moving at constant velocity, so it has zero acceleration. This means that the forces acting on it are balanced (net force = 0), so this is not the correct choice.
Therefore, the correct choice is
B) A car slowing as it reaches a traffic light.
Answer:
98.13m
Explanation:
Complete question
Daniel is 50.0 meters away from a building. Tip of the building makes an angle of 63.0° with the horizontal. What is the height of the building
CHECK THE ATTACHMENT
From the figure, using trigonometry
Tan(θ ) = opposite/adjacent
Where Angle (θ )= 63°
Opposite= X = height of the building
Adjacent= 50 m
Then substitute the values we have
Tan(63)= X/50
1.9626= X/50
X= 1.9626 × 50
X= 98.13m
Hence, the height of the building is 98.13m
