Can you guys plz help me

A person carries a plank of wood 1.9 m long with one hand pushing down on it at one end with a force F1 and the other hand holdi

BartSMP [9]

Solution :

Given :

mass of the plank, m = 14 kg

length of the plank, l = 1.9 m

Distance between $F_2$ and the end at which $F_1$ is acting, $r_2$ = 0.49 m

Torque exerted by the weight of the plank is given by :

$\tau_w= r_{\perp} \times F$

$=-\frac{1.9}{2} \times 14 \times 9.8$

= -130 Nm

The torque exerted by $F_1$ is

$\tau_1= r_{1} \times F_1$

$= 0 \times F_1$

= 0

Torque exerted by $F_2$ is

$\tau_2= r_{2} \times F_2$

$= 0.49 \times F_2$

$= 0.49 F_2$

Since the system is in equilibrium, the zero rotational acceleration occurs when the net external torque on the system is zero, i.e.

$\sum \tau = 0$

Therefore, we get

$$$\sum \tau= \tau_1+\tau_2+\tau_w$

$0= 0+0.49F_2+(-130)$

$F_2=\frac{130}{0.49}$

= 265 N (approx)

We know that zero linear acceleration occurs when the net external force is zero on the system to achieve equilibrium, i.e.

$\sum F = 0$

$\sum F = -F_1+F_2-mg=0$

$F_1=F_2-mg$

= 265 - (14 x 9.8)

= 128 N (approx)

3 0

3 years ago

A rod of mass M = 4 kg, length L = 1.8 meters, and moment of inertia ML2/12 is free to move on a frictionless surface. The rod i

Pachacha [2.7K]

Answer:

The speed of the rod's center of mass after the collision is 6 m/s.

Explanation:

Given that,

Mass of rod = 4 kg

Length l = 1.8 m

Moment of inertia $I=\dfrac{ML^2}{12}$

Mass of puck = 0.4 kg

Initial speed= 20 m/s

Distance = 0.3 m

Final speed = 10 m/s

(a). We need to calculate the speed v of the rod's center of mass after the collision

As there is no external force acting on the system so, linear and angular momentum of the system will be conserved.

Using conservation of momentum

$m_{i}v_{i}=m_{f}v_{f}+Mv$

Put the value into the formula

$0.4\times20=-0.4\times10+2v$

$v=\dfrac{8+4}{2}$

$v=6\ m/s$

Hence, The speed of the rod's center of mass after the collision is 6 m/s.

8 0

3 years ago

A sandbag motionless in outer space is hit by a three-times-as massive sandbag moving at 12 m/s. They stick together. This is an

vekshin1

Answer:

This is an example of inelastic collision and it loses zero(0) % of initial kinetic energy

Explanation:

Let the mass of the motionless sandbag = m₁

Let the mass of the moving sandbag = m₂ = 3m₁

initial velocity of the motionless sandbag, u₁ = 0

initial velocity of the moving sandbag, u₂ = 12 m/s

Let their final velocity, = v

Collision between two particles can either be elastic or inelastic.

Since they stick together after the impact, then the collision is inelastic

Apply the principle of conservation of linear momentum;

Initial kinetic energy = final kinetic energy

¹/₂m₁u₁² + ¹/₂m₂u₂² = ¹/₂v²(m₁ + m₂)

¹/₂m₁(0)² + ¹/₂(3m₁)(12)² = ¹/₂v²(m₁+3m₁)

216m₁ = 2m₁ v²

v² = 108

v = √108

v = 10.392 m/s

Change in kinetic energy = Final kinetic energy - initial kinetic energy

Initial Kinetic energy, KE₁ = ¹/₂m₁u₁² + ¹/₂m₂u₂²

KE₁ = ¹/₂m₁(0)² + ¹/₂(3m₁)(12)²

KE₁ = 216m₁ J

Final kinetic energy, KE₂ = ¹/₂v²(m₁ + m₂)

KE₂ = ¹/₂(108)(m₁ + 3m₁)

KE₂ = 216m₁ J

ΔKE = KE₂ - KE₁ = 216m₁ J - 216m₁ J = 0%

Therefore, this is an example of inelastic collision and it loses zero(0) % of initial kinetic energy

4 0

3 years ago

The diameter of a copper wire is thought to be approximately 0.3mm. Which instrument should be used to obtain a more accurate me

erica [24]

Answer:

C

Explanation:

The correct answer should be the micrometer.

The micrometer is an instrument that is capable of measuring the component of an object to very high precision. It is used to obtain accurate measurements in engineering.

In the case of the copper wire, the diameter of 0.3 mm was an approximation and a more accurate measure of the diameter would be obtained by using the micrometer.

The correct option is C.

4 0

3 years ago

The ability to navigate, hunt, and communicate by electric current in water most likely helps make up for the effect of dark, mu

fgiga [73]

The ability to navigate, hunt, and communicate by electric current in water most likely helps make up for the effect of vision. The answer to your question is VISION.

If fish live in a dark, murky water, that means that their sense of vision is affected. In dark, murky water they could not see anything. So, fish that lives in this kind of water developed the ability to o navigate, hunt, and communicate by electric current in water. This ability is known as electroreception. Among fish, electroreception is present in some sharks and rays, and electric eels.

I hope that this is the answer that you were looking for and it has helped you.

6 0

4 years ago

Can you guys plz help me ​

Can you guys plz help me