1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
Rus_ich [418]
1 year ago
6

Find the speed of a rock being thrown 20.5 meters (m) to the left in 4.0s.

Physics
2 answers:
erik [133]1 year ago
8 0

Answer:

5.125

Explanation:

formula for speed is distance/time distance measured in metres

Salsk061 [2.6K]1 year ago
3 0

Answer:

g

=

9.80

m/s

2

.

Although

g

varies from

9.78

m/s

2

to

9.83

m/s

2

, depending on latitude, altitude, underlying geological formations, and local topography, the average value of

9.80

m/s

2

will be used in this text unless otherwise specified. The direction of the acceleration due to gravity is downward (towards the center of Earth). In fact, its direction defines what we call vertical. Note that whether the acceleration

a

in the kinematic equations has the value

+

g

or

−

g

depends on how we define our coordinate system. If we define the upward direction as positive, then

a

=

−

g

=

−

9.80

m/s

2

, and if we define the downward direction as positive, then

a

=

g

=

9.80

m/s

2

.

One-Dimensional Motion Involving Gravity

The best way to see the basic features of motion involving gravity is to start with the simplest situations and then progress toward more complex ones. So we start by considering straight up and down motion with no air resistance or friction. These assumptions mean that the velocity (if there is any) is vertical. If the object is dropped, we know the initial velocity is zero. Once the object has left contact with whatever held or threw it, the object is in free-fall. Under these circumstances, the motion is one-dimensional and has constant acceleration of magnitude

g

.

We will also represent vertical displacement with the symbol

y

and use

x

for horizontal displacement.

KINEMATIC EQUATIONS FOR OBJECTS IN FREE FALL WHERE ACCELERATION = -G

v

=

v

0

−

g

t

y

=

y

0

+

v

0

t

−

 

1

2

 

g

t

2

v

2

=

v

2

0

−

2

g

(

y

−

y

0

)

Example 1: Calculating Position and Velocity of a Falling Object: A Rock Thrown Upward

A person standing on the edge of a high cliff throws a rock straight up with an initial velocity of 13.0 m/s. The rock misses the edge of the cliff as it falls back to earth. Calculate the position and velocity of the rock 1.00 s, 2.00 s, and 3.00 s after it is thrown, neglecting the effects of air resistance.

Strategy

Draw a sketch.

Velocity vector arrow pointing up in the positive y direction, labeled v sub 0 equals thirteen point 0 meters per second. Acceleration vector arrow pointing down in the negative y direction, labeled a equals negative 9 point 8 meters per second squared.

Figure 2.

We are asked to determine the position

y

at various times. It is reasonable to take the initial position

y

0

to be zero. This problem involves one-dimensional motion in the vertical direction. We use plus and minus signs to indicate direction, with up being positive and down negative. Since up is positive, and the rock is thrown upward, the initial velocity must be positive too. The acceleration due to gravity is downward, so

a

is negative. It is crucial that the initial velocity and the acceleration due to gravity have opposite signs. Opposite signs indicate that the acceleration due to gravity opposes the initial motion and will slow and eventually reverse it.

Since we are asked for values of position and velocity at three times, we will refer to these as

y

1

and

v

1

;

y

2

and

v

2

; and

y

3

and

v

3

.

Solution for Position  

y

1

1. Identify the knowns. We know that

y

0

=

0

;

v

0

=

13.0

m/s

;

a

=

−

g

=

−

9.80

m/s

2

; and

t

=

1.00

s

.

2. Identify the best equation to use. We will use

y

=

y

0

+

v

0

t

+

1

2

a

t

2

because it includes only one unknown,

y

(or

y

1

, here), which is the value we want to find.

3. Plug in the known values and solve for

y

1

.

y

1

=

0

+

(

13.0

m/s

)

(

1.00

s

)

+

 

1

2

 

(

−

9.80

m/s

2

)

(

1.00

s

)

2

=

8.10

m

Discussion

The rock is 8.10 m above its starting point at

t

=

1.00

s, since

y

1

>

y

0

. It could be moving up or down; the only way to tell is to calculate

v

1

and find out if it is positive or negative.

Solution for Velocity  

v

1

1. Identify the knowns. We know that

y

0

=

0

;

v

0

=

13.0

m/s

;

a

=

−

g

=

−

9.80

m/s

2

; and

t

=

1.00

s

. We also know from the solution above that

y

1

=

8.10

m

.

2. Identify the best equation to use. The most straightforward is

v

=

v

0

−

g

t

(from

v

=

v

0

+

a

t

, where

a

=

gravitational acceleration

=

−

g

).

3. Plug in the knowns and solve.

v

1

=

v

0

−

g

t

=

13.0

m/s

−

(

9.80

m/s

2

)

(

1.00

s

)

=

3.20

m/s

Discussion

The positive value for

v

1

means that the rock is still heading upward at

t

=

1.00

s

. However, it has slowed from its original 13.0 m/s, as expected.

Solution for Remaining Times

The procedures for calculating the position and velocity at

t

=

2.00

s

and

3.00

s

are the same as those above. The results are summarized in Table 1 and illustrated in Figure 3.

Time, t Position, y Velocity, v Acceleration, a

1.00 s 8.10 m 3.20 m/s −9.80 m/s2

2.00 s 6.40 m −6.60 m/s −9.80 m/s2

3.00 s −5.10 m −16.4 m/s −9.80 m/s2

Table 1. Results.

Graphing the data helps us understand it more clearly.

You might be interested in
Which of the following is NOT an indicator of a physical change?
S_A_V [24]

Answer:

1.  C.  The change is easily reversible

2. A.  a physical change

Explanation:

Happy Holidays

8 0
2 years ago
A net force, the magnitude of which is 3800 N, accelerates a 1260-kg vehicle for 10.0 s. The vehicle travels 50.0 m during this
Novay_Z [31]

Answer:

SEE EXPLANATION

Explanation:

p =  \frac{fd}{t}  \\ where \: \\p  = power \\  f = force \\ d = distance \\ and \: t = time \\  \\ p =  \frac{3800 \times 50}{10}  \\ p =  \frac{190000}{10}  \\ p = 19000w

7 0
3 years ago
What role do plants serve in the oxygen cycle
kodGreya [7K]
Plants,such as trees poduce oxygen to help animals like insects or humans can bresth snd surviave.
4 0
3 years ago
You are pushing a rock along level ground and making the rock speed up. How does the size of the force you exert on the rock com
Aneli [31]

Answer:

The forces are of the same magnitude just opposite directions

Explanation:

Newton's Third law tells us that if body A exerts a force on body B, then B exerts an equal but opposite force on body B. so as you continue to push the rock causing it to accelerate, the rock also continues to push back at you by an equal force in the opposite direction.

4 0
3 years ago
How can you decrease the amount of input force of a wheel and axle?
nasty-shy [4]

Explanation:

hmm by the increasing the size of wheel and decreasing axle

7 0
2 years ago
Other questions:
  • Theweight ofof body is 420N .Calculate its mass​
    10·1 answer
  • Spitting cobras can defend themselves by squeezing muscles around their venom glands to squirt venom at an attacker. Suppose a s
    12·1 answer
  • How far will 350 j raise a 7 kg mass?
    10·1 answer
  • the atoms in a sample are close together but can slide past one another. as the atoms lose energy, they move slower. the atoms b
    10·2 answers
  • Two objects separated by a distance r are each carrying a charge q The magnitude of the force exerted on the second object by th
    9·1 answer
  • The force between two very small charged bodies is found to be F. If the distance between them is tripled without altering their
    9·1 answer
  • 6.A truck drives to a rock quarry at a speed of 20 m/s. The truck takes on a load of
    15·1 answer
  • A woman falls to the ground while wearing a parachute. The air resistance on the parachute of the parachute is 500N. If the woma
    13·2 answers
  • Directions:
    10·1 answer
  • An engineer is working to design a bouncy ball that conserves all of its kinetic and potential energy. She drops the ball to the
    9·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!