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zhannawk [14.2K]
3 years ago
14

What is a car's acceleration between 25 s and 30 s?

Physics
1 answer:
Alex73 [517]3 years ago
7 0
I think you subtract them so you’ll get 5s
You might be interested in
B. A 20kg wagon is pulled up a 30° incline at an acceleration of 2.5ms?. The force pulling the wagon is parallel to the incline
yawa3891 [41]

The value of the coefficient of kinetic friction between the wagon and inclined surface is 0.78.

<h3>Coefficient of the kinetic friction</h3>

The value of coefficient of kinetic friction is calculated as follows;

F - Ff = ma

F - μmgcosθ = ma

where;

  • F is applied force
  • μ is coefficient of kinetic friction
  • m is mass of the wagon
  • a is acceleration of the wagon

182 - μ(20 x 9.8 x cos30) = 20(2.5)

182 - 169.74μ = 50

182 - 50 = 169.74μ

132 = 169.74μ

μ = 132/169.74

μ = 0.78

Thus, the value of the coefficient of kinetic friction between the wagon and inclined surface is 0.78.

Learn more about coefficient of friction here: brainly.com/question/20241845

7 0
2 years ago
Kinematics
leonid [27]

Answer:

a)

a = 2 [m/s^2]

b)

a = 1.6 [m/s^2]

c)

xt = 2100 [m]

Explanation:

In order to solve this problem we must use kinematics equations. But first we must identify what kind of movement is being studied.

a)

When the car moves from rest to 40 [m/s] by 20 [s], it has a uniformly accelerated movement, in this way we can calculate the acceleration by means of the following equation:

v_{f} = v_{i}+(a*t)

where:

Vf = final velocity = 40 [m/s]

Vi = initial velocity = 0 (starting from rest)

a = acceleration [m/s^2]

t = time = 20 [s]

40 = 0 + (a*20)

a = 2 [m/s^2]

The distance can be calculates as follows:

v_{f} ^{2} =  v_{i} ^{2}+(2*a*x)

where:

x1 = distance [m]

40^2 = 0 + (2*2*x1)

x1 = 400 [m]

Now the car maintains its speed of 40 [m/s] for 30 seconds, we must calculate the distance x2 by means of the following equation, it is important to emphasize that this movement is at a constant speed.

v = x2/t2

where:

x2 = distance [m]

t2 = 30 [s]

x2 = 40*30

x2 = 1200 [m]

b)

Immediately after a change of speed occurs, such that the previous final speed becomes the initial speed, the new Final speed corresponds to zero, since the car stops completely.

v_{f} = v_{i}-a*t

Note: the negative sign of the equation means that the car is stopping, i.e. slowing down.

0 = 40 - (a *25)

a = 40/25

a = 1.6 [m/s^2]

The distance can be calculates as follows:

v_{f} ^{2}  = v_{i} ^{2} -2*a*x3\\

0 = (40^2) - (2*1.6*x3)

x3 = 500 [m]

c)

Now we sum all the distances calculated:

xt = x1 + x2 + x3

xt = 400 + 1200 + 500

xt = 2100 [m]

8 0
3 years ago
A man is standing on the edge of a 20.0 m high cliff. He throws a rock horizontally with an initial velocity of 10.0 m/s. How lo
Arlecino [84]

Answer:

t = 4.08 s

R = 40.8 m

Explanation:

The question is asking us to solve for the time of flight and the range of the rock.

Let's start by finding the total time it takes for the rock to land on the ground. We can use this constant acceleration kinematic equation to solve for the displacement in the y-direction:

  • Δx = v_0 t + 1/2at²

We have these known variables:

  • (v_0)_y = 0 m/s
  • a_y = -9.8 m/s²
  • Δx_y = -20 m

And we are trying to solve for t (time). Therefore, we can plug these values into the equation and solve for t.

  • -20 = 0t + 1/2(-9.8)t²
  • -20 = 1/2(-9.8)t²
  • -20 = -4.9t²
  • t = 4.08 sec

The time it takes for the rock to reach the ground is 4.08 seconds.

Now we can use this time in order to solve for the displacement in the x-direction. We will be using the same equation, but this time it will be in terms of the x-direction.

List out known variables:

  • v_0 = 10 m/s
  • t = 4.08 s
  • a_x = 0 m/s

We are trying to solve for:

  • Δx_x = ?

By using the same equation, we can plug these known values into it and solve for Δx.

  • Δx = 10 * 4.08 + 1/2(0)(4.08)²
  • Δx = 10 * 4.08
  • Δx = 40.8 m

The rock lands 40.8 m from the base of the cliff.

7 0
2 years ago
A skydiver jumps out of a plane flying at an altitude of 5,500 meters. How fast is the skydiver going when they get to the groun
andrey2020 [161]

Answer:

2,500 feet (760 meters)

Explannation: <em>At about 2,500 feet (760 meters), the skydiver throws out a pilot chute, and it deploys the parachute. Its used to control the fall rate.</em>

4 0
3 years ago
Why do the golf ball have dimples?
Igoryamba

Answer:

HELLO! I WILL EXPLAIN WHY GOLF BALLS HAVE DIMPLES.

Explanation:

DIMPLES ON A GOLF BALL CREATE A THIN BOUNDARY LAYER OF AIR THAT CLINGS TO THE BALL'S SURFACE. THIS ALLOWS THE AIR TO FOLLOW THE BALL'S SURFACE A LITTLE FARTHER AROUND THE BACKSIDE OF THE BALL, THEREBY DECREASING THE SIZE OF THE WAKE.

I AM SO SORRY ABOUT THE CAP LOCKS I THINK MY CAP LOCKS BUTTON IS PUSHED, AND IT IS NOT POPPING UP FOR SOME REASON.

ANYWAYS, HAVE A GREAT DAY!!!!!!

4 0
2 years ago
Read 2 more answers
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