1 hour = 3,600 seconds
1 km = 1,000 meters
75 km/hour = (75,000/3,600) m/s = 20-5/6 m/s
The mean speed during the deceleration is
(1/2)(20-5/6 + 0) = 10-5/12 m/s.
Traveling at this average speed for 21 seconds,
the bus covers
(10-5/12) × (21) = 218.75 meters.
True. Explanation: In this instance, the area of the graph represents the impulse. Impulse is defined as the change in an object's momentum. Moreover, it is also expressed as the product of the force acting on an object and the duration of the impact. When we graph the force against time, if the force remains constant, the resultant graph will take on a rectangular shape, and the area under that graph will equal the impulse's definition.
The change in momentum (i.e., impulse) from the car during the collision remains constant regardless of whether an airbag is present. This is because the car's mass is unchanged, and the velocity change remains the same. Therefore, if the force is constant as F and reduced by a factor of 110, it follows that the collision duration must increase by the same factor when the airbag is utilized.
Both B and C are correct since they present identical options proposed in the question. Utilizing a lower gear in a vehicle aids in managing speed while descending a hill. It also helps preserve the brakes, which can overheat and lead to failures if overused on slopes. Shifting to a lower gear allows the engine to help reduce speed, although brakes may still be applied with less force. In this scenario, Stella should downshift to maintain control of her speed while descending the hill for safety.
