Answer:
C. both a speed and a direction
<h2>Answer: Resonance
</h2>
Resonance is a phenomenon that occurs when a body capable of vibrating is subjected to the action of a periodic force, whose frequency of vibration approaches the characteristic frequency of vibration (called resonance frequence) of said body. This is due a relatively small force applied in a repeated form, causing the amplitude of the oscillating system to become very large.
In other words, for the specific case of sound waves, this phenomenon occurs when the frequency of the wave that is external to the system or body coincides with the resonance frequency (characteristic frequency that reaches the maximum degree of oscillation) of this system or body.
In these circumstances the body vibrates, progressively increasing the amplitude of movement after each successive actions of the force. However, this effect can be destructive in some rigid materials.
The maximum acceleration the truck can have so that the refrigerator does not tip over is 4.15 m/s².
<h3>What will be the maximum acceleration of the truck to avoid tipping over?</h3>
The maximum acceleration is obtained by taking clockwise moments about the tipping point of rotation.
Clockwise moment = Anticlockwise moment
Ft * 1.58 m = F * 0.67 m
where
- Ft is tipping force = mass * acceleration, a
- F is weight = mass * acceleration due to gravity, g
m * a * 1.58 = m * 9.81 * 0.67
a = 4.15 m/s²
The maximum acceleration the truck can have so that the refrigerator does not tip over is 4.15 m/s².
In conclusion, the acceleration of the truck is found by taking moments about the tipping point.
Learn more about moments of forces at: brainly.com/question/27282169
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Average speed = total distance travelled ÷ total time taken
AS = (75km + 68km) ÷ (1hr + 2hr)
As = 143km ÷ 3hr
AS = 47.66667 km/hr
AS = 47.7 km/hr (3sf)