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A ball is thrown down vertically with an initial speed of 31 ft/s from a height of 40 ft. (a) What is its speed just before it s

ICE Princess25 [194]

Answer:

a. 41.96ft/s

b. 1.096s

Explanation:

a. v²=u²+2gs

v²=31²+2×10×40

V=41.96ft/s

b. t=(v-u) /g

t=(41.96-31)/10

t=1.096s

5 0

2 years ago

Help please

Anarel [89]

Answer:

1) D, 2) D, 3) B, 4) B, 5) C

Explanation:

You are asked to select the correct answer

1) The conservation of energy is one of the most important principles of physics that allows solving countless problems in life.

the correct answer is D

2) when a body falls, the gravitational potential energy is transformed into kinetic energy and both are transformed into thermal energy

the correct answer is D

3) When the gravitational potential energy is maximum, the kinetic energy is minimum and when the kinetic energy is maximum, the gravitational energy is minimum.

Correct answer B

4) speed is defined by

v = x / t

so the correct answer is B in the SI system

5) when we repeat a measurement several times, the random or statistical errors decrease, therefore the confidence of the measurement increases.

The correct answer is C

4 0

2 years ago

Mila both 2 kg of cheese in the market to be used for her Mac and cheese recipe. How many pounds does a 2.00 kg of cheese weigh?

gogolik [260]

Answer:

The answer is 4 pounds

Explanation:

The explanation is that 1 kilogram is equal to 2 pounds so multiply the kilogram with the 1 pound

8 0

2 years ago

A student, who weighs 720N, is standing on a bathroom scale and riding an elevator that is moving downwards with a speed that is

jasenka [17]

Answer:

1) The mass of the student is approximately 73.39 kg

2) The net force on the student is approximately 947.523 N

3) The value the scale will read is approximately 96.59 kg

Explanation:

The given parameters are;

The weight of the student = 720 N

The speed at which the elevator is decreasing = 3.1 m/s²

1) The weight of the student = The mass of the student × The acceleration due to gravity

The acceleration due to gravity is a constant = 9.81 m/s²

Substituting the known values gives;

720 N = The mass of the student × 9.81 m/s²

∴ The mass of the student = 720 N/(9.81 m/s²) ≈ 73.39 kg

2) The forces acting on the student are;

i) The force of gravity which is the weight of the student acting downwards

ii) The inertia force of the slowing elevator acting downwards in the same direction as the weight of the student

The net force, $F_{net}$ = The weight of the student + The inertia force of the slowing elevator

∴ The net force, $F_{net}$ = 720 N + 73.39 kg × 3.1 m/s² ≈ 947.523 N

3) The scale will read the mass of the student as follows;

Mass reading of student on the scale = Force on scale/9.81

∴ Mass reading of student on the scale = 947.523/9.81 ≈ 96.59 kg

The value the scale will read = 96.59 kg.

3 0

2 years ago

A 1000-kg car is driving toward the north along a straight horizontal road at a speed of 20.0 m/s. The driver applies the brakes

Nitella [24]

Answer:

The value of F= - 830 N

Since the force is negative, it implies direction of the force applied was due south.

Explanation:

Given data:

Mass = 1000-kg

Distance, d = 240 m

Initial velocity, v1 = 20.0 m/s

Final velocity, v2 = 0 (since the car came to rest after brake was applied)

v2²= v1² + 2ad (using one of the equation of motion)

0= 20² + (2 x a x 240)

0= 400 + 480 a

a = - 400/480

a = - 0.83 m/s²

Then, imputing the value of a into

F = ma

F = 1000 kg x ( - 0.83 m/s²)

F= - 830 N

The car was driving toward the north, and since the force is negative, it implies direction of the force applied was due south.

3 0

2 years ago