Agility is the

Which accurately explains concave and convex lenses?

barxatty [35]

Answer:

its C! I just finished the test on edg :)

3 0

3 years ago

Read 2 more answers

A person throws a ball straight up into the air with a speed of 7.3m/s. How high does the ball go?

Colt1911 [192]

Answer:

2.6645m

Explanation:

applying motion equations we can find the answer,

$v^{2}=u^{2} +2as$

Let assume ,

u = starting speed(velocity)

v = Final speed (velocity)

s = distance traveled

a = acceleration

by the time of reaching the highest point subjected to the gravity , the speed should be equal to zero

we consider the motion upwards , in this case the gravitational acceleration should be negative in upwards (assume g =10 m/s2 downwards)

that is,

$v^{2}=u^{2} +2as\\0=7.3^{2} -2*10*s\\s=2.6645m$

4 0

3 years ago

A gardener pushes a 20 kg lawnmower whose handle is tilted up 37∘ above horizontal. The lawnmower's coefficient of rolling frict

e-lub [12.9K]

Answer:

58.4 W

Explanation:

The speed of the lawnmower is constant: this means that its acceleration is zero, so the net force on it is zero.

The equation of the forces along the two directions therefore are:

- Perpendicular to the floor: $F sin \theta + R -mg =0$

- Parallel to the floor: $F cos \theta - \mu R = 0$

where

F is the push of the gardener

R is the normal reaction

m = 20 kg is the mass

g = 9.8 m/s^2 is the acceleration of gravity

$\mu=0.18$ is the coefficient of friction

$\theta=37^{\circ}$

Solving for R,

$R=mg-Fsin \theta$

Substituting into the other equation,

$F cos \theta - \mu (mg-Fsin \theta) = 0\\F cos \theta - \mu mg + \mu F sin \theta = 0\\F(cos \theta+\mu sin \theta)=\mu mg\\F=\frac{\mu mg}{cos \theta + \mu sin \theta}=\frac{(0.18)(20)(9.8)}{cos 37^{\circ}+0.18(sin 37^{\circ})}=38.9 N$

And the power he must supply therefore is the product of this force and the speed:

$P=Fv=(38.9)(1.5)=58.4 W$

7 0

3 years ago

A scientist makes a device to catch baseballs. A long bar of total mass 2.2kg and length 1.2m is fixed at its center. It catches

Valentin [98]

Answer:

ωf = 4.53 rad/s

Explanation:

By conservation of the angular momentum:

Ib*ωb = (Ib + Ic)*ωf

Where

Ib is the inertia of the ball

ωb is the initial angular velocity of the ball

Ic is the inertia of the catcher

ωf is the final angular velocity of the system

We need to calculate first Ib, Ic, ωb:

$Ib = mb*(L/2)^2=0.15*(1.2/2)^2=0.054 kg.m^2$

$Ic = mc/12*L^2=2.2/12*1.2^2=0.264 kg.m^2$

ωb = Vb / (L/2) = 16 / (1.2/2) = 26.67 m/s

Now, ωf will be:

$\omega f = \frac{Ib*\omega b}{Ib + Ic} = 4.53rad/s$

8 0

3 years ago

An electromagnetic wave with frequency 65.0Hz travels in an insulating magnetic material that has dielectric constant 3.64 and r

lakkis [162]

Answer:

The wavelength of the wave is $1.06\times10^6 m$

Explanation:

Lets calculate

We know an electromagnetic wave is propagating through an insulating magnetic material of dielectric constant K and relative permeability $K_m$ ,then the speed of the wave in this dielectric medium is $\nu$ is less than the speed of the light c and is given by a relation

$\nu=\frac{c}{\sqrt{KK_m} }$ --------- 1

In case the electromagnetic wave propagating through the insulating magnetic material , the amplitudes of electric and magnetic fields are related as -

$E_m_a_x= \nu B_m_a_x$