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suter
2 months ago
13

An object is at rest on the ground. The object experiences a downward gravitational force from Earth. Which of the following pre

dictions is correct about why the object does not accelerate downward? Select two answers. Justify your selections.A) The bonded molecules of the object are repelled upward by the bonded molecules of the ground with the same magnitude as the gravitational force downward on the object.B)The normal force is exerted upward on the object from the ground with the same magnitude as the gravitational force downward on the objectC) The bonded molecules of the object are attracted downward by the bonded molecules of the ground with the same magnitude as the gravitational force downward on the object.D) The force of friction is exerted upward on the object from the ground with the same magnitude as the gravitational force downward on the object.
Physics
2 answers:
Yuliya22 [3.3K]2 months ago
6 0

Answer:

A) and B) are valid.

Explanation:

When an object remains at rest, it is indicative that no net force acts upon it.

The downward gravitational force from Earth must be counterbalanced by an upward force of equal magnitude in order to maintain rest.

This upward force is provided by the normal force, which adjusts to satisfy Newton’s 2nd Law and is always perpendicular to the surface supporting the object (in this instance, the ground).

At the molecular level, this normal force comes from the ground's bonded molecules acting like tiny springs, compressed by the object’s molecules, providing an upward restorative force.

Thus, statements A) and B) are true.

serg [3.5K]2 months ago
4 0

Answer:

The bonded molecules in the object are pushed upwards by the bonded molecules in the ground, matching the gravitational force pulling down on the object.

The ground exerts a normal force upwards on the object, equal to the gravitational force acting downwards on it.

Explanation:

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You are an investigator at the scene of a car crash. A Volvo of has hit an Alpha Romeo from the side and the two are inter-tangl
serg [3582]

Answer:

Let the Volvo's speed upon braking be v, and its mass be m1.

The speed of the Volvo just before the crash is represented as v1.

After applying the brakes, the skidding distance is noted as 30 m.

The equation governing this scenario is v1^2- v^2 = - 2 * a * s, where a= represents deceleration and s= denotes skidding distance.

Assuming the deceleration to be -0.3 g = - 2.94 m/s^2 (as provided by the Volvo website for the car's emergency system).

The equation can be modified to solve for v: v^2 = v1^2 + (2 * a * s )= v1^2 + 176.4.

After the collision, both vehicles merge and proceed together (m1+m2) at an initial speed of V (let's say).

They then move 12.25 m and eventually come to a stop.

Using the equation (0)^2 -(V)^2 = - 2 * a' * s', where a' signifies the combined deceleration and s' denotes the distance traveled by the two cars.

Let's assume the combined system’s deceleration is notably higher at (- g).

Utilizing the format V^2 = 2 * 9.8 * 12.25.

This results in V = 15.5 m/s.

Using momentum conservation in the X direction (East): m1 * v1 = (m1+ m2) * V * cos 15.

Solving for v1 gives: v1 = (1650+ 975) Kg * 15.5 m/s * cos 15 /1650 Kg = 23.8 m/s.

Hence, v^2 = V1^2 + 176.4 = (23.8)^2 + 176.4.

This results in v = 27.3 m/s = 61.1 mph (indicating that he exceeded the speed limit when applying the brakes).

In the Y-direction momentum conservation shows: m2 * v2 = (m1+m2) * V * sin 15.

Solving for v2 results in: v2 = (m1+m2) * V * sin 15/m2.

We conclude with v2 = 41.7 m/s (93.3 m/hr) indicating he also exceeded the speed limit.

5 0
2 months ago
Read 2 more answers
Two experiments are performed on an object to determine how much the object resists a change in its state of motion while at res
inna [3103]

Answer:

The first experiment measures inertial mass, while the second experiment measures gravitational mass.

Explanation:

A student conducts two different experiments to observe resistance to changes in motion, both when at rest and in motion.

In the initial experiment, an object is forcefully pushed against a flat surface while its speed is tracked by a sensor. This setup involves work done against the object's inertia, identifying the mass as inertial mass.

Conversely, in the subsequent experiment, the object is lifted or thrown upward with an applied force and the speed is recorded. Here, the mass refers to gravitational mass, as the work performed combats gravity or the object's weight.

5 0
2 months ago
A running mountain lion can make a leap 10.0 mlong, reaching a maximum height of 3.0 m. What is the speed of the mountain lion j
ValentinkaMS [3465]

To tackle this question we will apply the kinematic equations that describe the motion of a projectile, where both maximum height and distance traveled are defined. This scenario demonstrates a lion achieving a height (H) of 3m and covering a horizontal distance (R) of 10m. The equations governing this kind of motion are expressed as follows:

H = \frac{v_0^2sin^2\theta}{2g}

R = \frac{v_0^2 sin 2\theta}{g}

By dividing the two equations, we determine:

\frac{H}{R}=\frac{\frac{v_0^2sin^2\theta}{2g}}{\frac{v_0^2 sin 2\theta}{g}}

\frac{H}{R}= \frac{sin^2\theta}{2}*\frac{1}{sin2\theta}

\frac{H}{R}= \frac{sin^2\theta}{2}*\frac{1}{2sin\theta cos\theta}

\frac{H}{R}= \frac{1}{4} \frac{sin\theta}{cos\theta}

\frac{H}{R}= \frac{1}{4} tan\theta

Plugging in the values for H and R yields:

\frac{3}{10} = \frac{1}{4} tan\theta

\theta = tan^{-1} \frac{12}{10}

\theta = 50.2\°

After substituting \theta into the relevant equation, we find:

H = \frac{v_0^2sin^2\theta}{2g}

v_0^2 = \frac{H 2g}{sin^2\theta}

v_0^2 = \frac{3*2*9.8}{sin^2(50.2)}

v_0^2 = 99.62

v_0 = \sqrt{99.62}

v_0 = 9.98m/s

In conclusion, the mountain lion's launch speed upon takeoff is approximately 9.98m/s at an angle of 50.2°.

5 0
2 months ago
The drawing shows an adiabatically isolated cylinder that is divided initially into two identical parts by an adiabatic partitio
Yuliya22 [3333]

Answer:

the temperature on the left side is 1.48 times greater than that on the right

Explanation:

GIVEN DATA:

\gamma = 5/3

T1 = 525 K

T2 = 275 K

It is known that

P_1 = \frac{nRT_1}{v}

P_2 = \frac{nrT_2}{v}

n and v are constant on both sides. Therefore we have

\frac{P_1}{P_2} = \frac{T_1}{T_2} = \frac{525}{275} = \frac{21}{11}

P_1 = \frac{21}{11} P_2..............1

let the final pressure be P and the temperature T_1 {f} and T_2 {f}

P_1^{1-\gamma} T_1^{\gamma} = P^{1 - \gamma}T_1 {f}^{\gamma}

P_1^{-2/3} T_1^{5/3} = P^{-2/3} T_1 {f}^{5/3}..................2

similarly

P_2^{-2/3} T_2^{5/3} = P^{-2/3} T_2 {f}^{5/3}.............3

divide equation (2) by equation (3)

\frac{21}{11}^{-2/3} \frac{21}{11}^{5/3} = [\frac{T_1 {f}}{T_2 {f}}]^{5/3}

T_1 {f} = 1.48 T_2 {f}

thus, the left side temperature equals 1.48 times the right side temperature

6 0
2 months ago
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