1. What is the most direct type of heat transfer? radiation conduction

A homeowner is trying to move a stubborn rock from his yard. By using a a metal rod as a lever arm and a fulcrum (or pivot point

pogonyaev

Answer:

L = 1.545 m

Explanation:

Let the total length of the rod is L

now the torque must applied on the other end of the rod so that it will balance the torque due to weight of rock on other side of fulcrum

so we will have

$mg \times d = F(L - d)$

so we have

$325\times 9.8 \times 0.266 = F(L - 0.266)$

F = 663 N

$848 = 663(L - 0.266)$

$L = 1.545 m$

6 0

3 years ago

Indicate whether the statement is true or false. A force can be simply defined as a push or a pull.

Sidana [21]

This B: False, because the definition is lacking.

Force is when two objects interact with one another causing it to either move or not move. In our daily lives there are a lot of times force is exerted upon us, rather force is everywhere and here are the evidences:

*Pushing a cart
*Pushing a wall
*Hitting a baseball bat
*Apple falling down from a tree.
*Balls hitting one another
*A swinging pendulum
*Throwing a paper with stone above it
*Breaking of glass in the floor
*Falling of leaves on the grass

5 0

4 years ago

Calculate the work done by the cyclist when his power output is 200 W for 1800 seconds.

Kobotan [32]

Answer:

3.6 × 10^5 J

Explanation:

Work Done = Energy

Energy = Power × time

Energy = 200 × 1800

= 360000 J

W =

$3.6 \times 10 {}^{5} j$

3 0

3 years ago

Through what potential difference would you need to accelerate an alpha particle, starting from rest, so that it will just reach

Svetlanka [38]

Answer:

$\Delta V = 1.8 \times 10^7 V$

Explanation:

GIVEN

diameter = 15 fm = $15 \times 10^{-15}$ m

we use here energy conservation

$K_{i}+U_{i} =K_{f}+U_{f}$

there will be some initial kinetic energy but after collision kinetic energy will zero

$K_{i} + 0 = 0 + \frac{1}{4 \pi \epsilon _{0}} \frac{(2e)(92e)}{7.5 \times 10^{-15}}$

on solving these equations we get kinetic energy initial

$KE_{i} = 5.65\times 10 ^{-12} \times \frac {1 eV}{1.6 \times 10^{-19}}$

$KE_{i} = 35.33$ J ..............(i)

That is, the alpha particle must be fired with 35.33 MeV of kinetic energy. An alpha particle with charge q = 2 e

and gains kinetic energy K =e∆V ..........(ii)

by accelerating through a potential difference ∆V

Thus the alpha particle will

just reach the ${238}_U$ nucleus after being accelerated through a potential difference ∆V

equating (i) and second equation we get

e∆V = 35.33 Me V

$\Delta V = \frac{35.33}{2} MV\\\Delta V = 1.8 \times 10^7 V$

7 0

3 years ago

A small boat coasts at constant speed under a bridge. A heavy sack of sand is dropped from the bridge onto the boat. The speed o

Tju [1.3M]

Answer:

d. decreases

Explanation:

The law of conservation of momentum tells us that the sum of momenta before the collision is equal to the sum of momenta after the collision. The bag has no momentum as it falls onto the boat because its velocity is zero in the horizontal direction. But after it hits the boat, it's momentum increases while the momentum of the system remains the same. That means a component of the system must decrease somewhere else. And that component is the velocity, not the mass, of the boat.

7 0

3 years ago