Physics, 13.04.2020 15:37 SoccerHalo

While traveling along the highway a driver slows from 50m/s to 20 m/s in 10 seconds. What is the driver’s acceleration?

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Answer from: Madisonaubrey22

Answer

-3 $\frac{m}{s^2}$

Explanation

Acceleration is the rate of change in velocity over time, or how greatly an object speeds up or down per unit of time. This is a vector quantity, so it has both magnitude and direction. Knowing this, we can create an equation for acceleration that shows the relationship between velocity and time.

Since acceleration is change in velocity over time, or per unit of time, we can write this as a = Δv/t.

a represents acceleration in meters per second squared ( $\frac{m}{s^2}$ )

Δv represents change in velocity in meters per second ( $\frac{m}{s}$ )

t represents time in seconds (s)

This is because as each unit of time passes, the velocity changes by the acceleration value. For example, if the acceleration is 2 $\frac{m}{s^2}$ , and the object starts at 5 $\frac{m}{s}$ , one second later, the object will be moving at a velocity of 2 + 5 = 7 $\frac{m}{s}$ .

Note that the change in velocity can also be written as v_f-v_o where $v_f\\$ is the final velocity and v_o is the initial velocity, since the change in velocity is the difference between the initial and final velocities.

So our equation a = Δv/t becomes a = $\frac{v_f-v_o}{t}$

Now that we have an equation, we can plug in values and use algebra to solve. In the question the given values are an initial velocity ( v_o ) of 50 $\frac{m}{s}$ , a final velocity ( v_f ) of 20 $\frac{m}{s}$ , and a time (t) of 10 seconds.

a = $\frac{v_f-v_o}{t}$

a = $\frac{20-50}{10}$

a = $\frac{-30}{10}$

a = -3 $\frac{m}{s^2}$

The acceleration of the driver is -3 $\frac{m}{s^2}$ . Note that this value is negative, because the velocity decreases over time. This matches the information in the question that states that the driver slows down. The negative sign indicates the direction of acceleration, which is opposite the direction of motion and velocity. If acceleration were positive, the acceleration would be in the same direction of motion and velocity of the driver. The absolute value of acceleration, | -3 | = 3, indicates the magnitude of acceleration.

Answer from: Quest

work: w = fd (given)

work done by chet =50*1 = 50 j

work done by mika =40*2 = 80 j

work done by sara =30*1.5 = 45 j

work done by bill =60*0.5 = 30 j

students in order from the greatest amount of work done to the least is mika> chet> sara> bill

hence option (b) is correct.

Answer from: Quest

float.

archimedes' principle

denser than water sinks in water.

denser than mercury would sink in it

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While traveling along the highway a driver slows from 50m/s to 20 m/s in 10 seconds. What is the dri...

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