Question

level 3 q1 a skateboarder skates down a ramp for 3 seconds. if his initial velocity was 0.8 m/s and his final velocity was 7 m/s, what was his acceleration? a. 0.5 m/s² b. -0.5 m/s² c. 2.1 m/s² d. -2.1 m/s² level 3 q2 a balloon moves vertically upward at 5 m/s. this is an example of a. speed b. velocity c. acceleration d. velocity and acceleration level 3 q3 the fastest human on earth ran an impressive 44.7 km/h (27.8 mph). this is an example of a. speed b. velocity c. acceleration d. none of the above level 3 q4 a car moving 20 m/s accelerates to pass a truck. five seconds later the car is moving 30 m/s. what is the acceleration of the car? a. 5 m/s b. -5 m/s c. -2 m/s d. 2 m/s

Explanation:

Q1

Step1: Recall the acceleration formula

The formula for acceleration is \(a=\frac{v - u}{t}\), where \(v\) is the final velocity, \(u\) is the initial velocity, and \(t\) is the time.

Step2: Substitute the given values

Given \(u = 0.8\ m/s\), \(v=7\ m/s\), and \(t = 3\ s\).

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Q2

Velocity is a vector quantity that has both magnitude and direction. The balloon is moving vertically upward (direction) at \(5\ m/s\) (magnitude). Speed is a scalar (only magnitude), and there is no indication of a change in velocity (so no acceleration).

Q3

Speed is a scalar quantity (only magnitude). The value \(44.7\ km/h\) only gives the magnitude of the rate of motion. Velocity would require a direction, and acceleration would require a change in velocity.

Q4

Step1: Use the acceleration formula

The formula \(a=\frac{v - u}{t}\), with \(u = 20\ m/s\), \(v = 30\ m/s\), and \(t=5\ s\).

Step2: Calculate the acceleration

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Answer:

Q1: C. \(2.1\ m/s^{2}\)
Q2: B. Velocity
Q3: A. Speed
Q4: D. \(2\ m/s\)