Physics, 01.01.2021 20:00 Jrbizkit

A racing car starts from rest at t=0 and reaches a final speed v at time t. If the acceleration of the car is constant during this time, which of the following statements are true? a) the average speed of the car is v/2; b) the car travels a distance vt; c) the magnitude of the acceleration of the car is v/t; d) the velocity of the car remains constant; or e) none of the statements is true

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All true statements are shown: a) The average speed of the car is $\frac{v}{2}$ , c)The magnitude of the acceleration of the car is $\frac{v}{t}$ .

Explanation:

Let prove the validity of each statement:

a) The average speed of the car is $\frac{v}{2}$ .

The average speed ( $\bar v$ ) is defined by the following formula:

$\bar v = \frac{v_{o}+v_{f}}{2}$ (1)

Where:

$v_{o}$ , $v_{f}$ - Initial and final speeds of the racing car.

If we know that $v_{o} = 0$ and $v_{f} = v$ , then the average speed of the racing car:

$\bar v = \frac{0+v}{2}$

$\bar v = \frac{v}{2}$

The statement is true.

b) The car travels a distance $v\cdot t$ .

Since the racing car is accelerating uniformly, the distance travelled by the car is represented by the following kinematic formula:

$x - x_{o}=v_{o}\cdot t + \frac{1}{2}\cdot a\cdot t^{2}$ (2)

Where is the acceleration of the racing car, measured in meters per square second.

The statement is false.

c) The magnitude of the acceleration of the car is $\frac{v}{t}$ .

Since the racing car is accelerating uniformly, the velocity of the racing car is represented by the following kinematic formula:

$v_{f} = v_{o}+a\cdot t$ (3)

Then, we clear the acceleration of the expression:

$a = \frac{v_{f}-v_{o}}{t}$

If we know that $v_{o} = 0$ and $v_{f} = v$ , then the acceleration of the car is:

$a = \frac{v-0}{t}$

$a = \frac{v}{t}$

The statement is true.

d) The velocity of the car remains constant.

Since the car accelerates uniformly, the vehicle does not travel at constant velocity.

The statement is false.

Answer from: Quest

freezing

deposition

condensation

explanation;

melting also called fusion is the process where solid becomes liquid, sublimation is the process where solid becomes gaseous without first changing to liquid, deposition involves change from gaseous to solid state, freezing involves change from liquid to solid, boiling or evaporation involves change of liquid to gaseous state, while condensation is the change from gaseous state to liquid state.

endothermic reactions involves absorption of heat from the surroundings or the environment while exothermic reactions involves loss of heat energy to the surroundings.

in this case, sublimation, evaporation and melting are endothermic reactions (gain energy from the environment) while, freezing, deposition and condensation are exothermic (loss of energy to the surroundings) reactions.

Answer from: Quest

measure their densities same density, same sub

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A racing car starts from rest at t=0 and reaches a final speed v at time t. If the acceleration of t...

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