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3 years ago

Can you have a positive velocity but a negative acceleration? I need this to complete my physics hw :/

1 answer:

8 0

Answer: Positive velocity is then speed towards right, and negative velocity is speed towards left. It is the same for acceleration: negative acceleration is acceleration towards left. It slows objects moving towards right

Explanation: In physics calculations, acceleration — just like displacement and velocity — can be positive or negative. can u help me now pls ?

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A 1500 kg car decelerates from an initial velocity of 19 m/s to a skidding stop. If the coefficient of kinetic friction is 0.100

Stella [2.4K]

Answer:

19.4 seconds

Explanation:

We have:

m: mass of the car = 1500 kg

v₀: is the initial speed = 19 m/s

$v_{f}$ : is the final speed = 0 (it stops)

$\mu_{k}$ : is the coefficient of kinetic friction = 0.100

First, we need to find the acceleration by using the second Newton's law:

$\Epsilon F = ma$

$-\mu_{k}N = ma$

$-\mu_{k}mg = ma$

Solving for a:

$a = -\mu_{k}g = -0.1*9.81 m/s^{2} = -0.981 m/s^{2}$

Now we can find the time until it stops:

$v_{f} = v_{0} + at$

Solving for t:

$t = \frac{v_{f} - v_{0}}{a} = \frac{-(19 m/s)}{-0.981 m/s^{2})} = 19.4 s$

Therefore, the time until it stops is 19.4 seconds.

I hope it helps you!

7 0

3 years ago

2. Another car weighs 2000kg, you can push it .05 m/s?, how much force are you

Vesna [10]

Answer:

$\boxed {\boxed {\sf 100 \ Newtons}}$

Explanation:

We are asked to calculate the force you are applying to a car. According to Newton's Second Law of Motion, force is the product of mass and acceleration. Therefore, we can use the following formula to calculate force.

$F= m \times a$

The mass of the car is 2000 kilograms and the acceleration is 0.5 meters per second squared.

m= 2000 kg
a= 0.05 m/s²

Substitute the values into the formula.

$F= 2000 \ kg \times 0.05 \ m/s^2$

Multiply.

$F= 100 \ kg *m/s^2$

Convert the units. 1 kilogram meter per second squared is equal to 1 Newton. Our answer of 100 kilogram meters per second square is equal to 100 Newtons.

$F= 100 \ N$