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What force is needed to give a mass of 20kg an acceleration of 5.0m/s?

Marysya12 [62]

Answer:

a=5

m= 20

F= m×a

20×5

=100N

5 0

3 years ago

A 70-cm-diameter wheel accelerates uniformly from 160rpm to 280rpm in 4.0s. Determine (a) its angular acceleration, and (b) the

poizon [28]

Explanation:

Given that,

Diameter of the wheel, d = 70 cm = 0.7 m

Initial angular speed, $\omega_i=160\ rpm=16.75\ rad/s$

Final angular speed, $\omega_f=280\ rpm=29.32\ rad/s$

Time, t = 4 s

(a) Angular acceleration,

$\alpha =\dfrac{\omega_f-\omega_i}{t}\\\\\alpha =\dfrac{29.32-16.75}{4}\\\\\alpha =3.14\ rad/s^2$

(b) Tangential acceleration is :

$a=r\alpha \\\\a=0.35\times 3.14\\\\a=1.085\ m/s^2$

Angular speed of the wheel after 2 seconds is :

$\omega_f=\omega_i+\alpha t\\\\\omega_f=16.75+3.14\times 2\\\\\omega_f=23.03\ rad/s$

Radial acceleration will be :

$a=\omega_f^2r\\\\a=(23.03)^2\times 0.35\\\\a=185.6\ m/s^2$

Hence, this is the required solution.

4 0

3 years ago

If a projectile is launched vertically from the Earth with a speed equal to the escape speed, how high above the earth's surface

Alecsey [184]

Answer: h = 3R

Explanation:

Using the law of conservation of energy,

Total energy at the beginning of the launch would be equal to total energy at any point.

kinetic energy + gravitational potential energy = constant

Initial energy of the projectile = $\frac{1}{2}mv_e^2-\frac{GMm}{R}$ ... (1)

where R is the radius of the Earth, M is the mass ofthe Earth, m is the mass of the projectile.

escape velocity, $v_e=\sqrt{\frac{2GM}{R}}$

Total energy at height h above the Earth where speed of the projectile is half the escape velocity:

$\frac{1}{2}m(v_e/2)^2-G\frac{Mm}{R+h}$ ...(2)

(1)=(2)

⇒ $\frac{1}{2}m(v_e/2)^2-G\frac{Mm}{R+h} = \frac{1}{2}mv_e^2-\frac{GMm}{R}$

⇒ $G\frac{Mm}{R}-G\frac{Mm}{R+h}= \frac{1}{2}m \frac{3}{4}v_e^2 =\frac{1}{2}m \frac{3}{4} (\sqrt{\frac{2GM}{R}})^2$

⇒ $\frac{GM(R+h-R)}{R(R+h)} = \frac{3}{4}(\frac{GM}{R})$

⇒ $\frac{h}{R+h} = \frac{3}{4}$

⇒h = 3R

Thus, at height equal to thrice radius of Earth, the speed of the projectile would reduce to half of escape velocity.

4 0

3 years ago

Read 2 more answers

A speedometer of a car reads a constant 60 km per hour while negotiating a curve. Which of the following could NOT be true?

seraphim [82]

Answer:

A

Explanation:

3 0

3 years ago

A curve that has a radius of 100 m is banked at an angle of θ = 10.4 ∘ . If a 1200 kg car navigates the curve at 65 km / h witho

Vika [28.1K]

Explanation:

Below is an attachment containing the solution.

3 0

3 years ago