Help me

Which of the following statements are true at some time during the course of the motion? Check all that apply. Check all that ap

eduard

Answer:

The object can have zero velocity and, simultaneously, nonzero acceleration.

The object can have zero acceleration and, simultaneously, nonzero velocity.

The object can have nonzero velocity and nonzero acceleration simultaneously.

Explanation:

An object in simple harmonic motion has a total mechanical energy (sum of elastic potential energy and kinetic energy) that is constant:

E=U+K=1/2kx^2 + 1/2}mv^2

where,

k is equal to the spring constant

x is equal to the displacement

m is the mass

v is the speed

We can note that the force on the spring is given by Hook's law:

F=-kx

In Newton's law F = ma, this can be also be written as

ma=-kx

a=-k/mx

This implies that the acceleration is proportional to the displacement.

From the first equation, we can now states that:

When the displacement is zero, x=0, the acceleration is zero, a=0, and the velocity is maximum

When the velocity is zero, v=0, the acceleration is maximum, which occurs when the displacement is maximum

In all the other intermediate situations, both velocity and acceleration are nonzero.

So the correct answers are

The object can have zero acceleration and, simultaneously, nonzero velocity.

The object can have nonzero velocity and nonzero acceleration simultaneously.

The object can have zero velocity and, simultaneously, nonzero acceleration.

4 0

3 years ago

Read 2 more answers

José and Laurel measured the length of a stick's shadow during the day. Without knowing the length of the stick, which of their

skelet666 [1.2K]

Answer:

Option B.

Explanation:

Assuming the stick is in vertical position, its shadow depends on two factors: its length and the angle between the sun rays and the stick. When the angle is bigger, the lenght of the shadow increases, and vice versa. So, when the sun rays are parallel to the stick, the shadow may be small. Since they are nearly perpendicular to the Earth's surface at 12 o'clock, the shadow of the stick at that time should be minimal. It means that the measured shadow of 75 cm at 12:30 p.m. is almost impossible (Option B).

5 0

3 years ago

You are in charge of designing a movie stunt for a new Fast and Furious film. In this scene a stunt person has to jump from a br

blondinia [14]

Answer:

103.5 meters

Explanation:

Given that a stunt person has to jump from a bridge and land on a boat in the water 22.5 m below. The boat is cruising at a constant velocity of 48.3 m/s towards the bridge. The stunt person will jump up at 6.45 m/s as they leave the bridge.

The time the person will jump to a certain spot under the bridge can be calculated by using the formula below:

h = Ut + 1/2gt^2

since the person will fall under gravity, g = 9.8 m/s^2

Also, let assume that the person jump from rest, then, U = 0

Substitute h, U and g into the formula above

22.5 = 1/2 * 9.8 * t^2

22.5 = 4.9t^2

t^2 = 22.5/4.9

t^2 = 4.59

t = $\sqrt{4.592}$

t = 2.143 seconds

From definition of speed,

speed = distance /time

Given that the boat is cruising at a constant velocity of 48.3 m/s towards the bridge, substitute the speed and the time to get the distance.

48.3 = distance / 2.143

distance = 48.3 * 2.143

distance = 103.5 m

Therefore, the boat should be 103.5m away from the bridge at the moment the stunt person jumps?

3 0

3 years ago

What do you think would be the most important thing to know about understanding the life of Sioux (Lakota) children?

Tcecarenko [31]

The main idea word to know is the Life of Sioux (Lakota) children

4 0

4 years ago

Chuck drove 35mi from Austin to San Marcos in 40min, stopped 30min for a hamburger, and then drove 45mi to San Antonio in 50min.

Effectus [21]

Answer:

his average speed was 40 miles per hour

5 0

3 years ago