1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
Aleksandr [31]
2 years ago
9

Can someone help me with these two? Pls

Physics
1 answer:
Gelneren [198K]2 years ago
8 0
For the first one: A falling object has higher gravitational potential energy and as it falls this decreases but kinetic energy increases. As the object hits the floor, energy is transferred to heat and sound.

42*9.8*12= 4939.2
Kinetic energy = 4939.2 OR 4939

To find the final speed use the kinetic energy formula;

Ek = 1/2 MV2

4939=1/2*42*v2
V2= 4939 divided by (1/2 * 42)
V2= 4939 / 21
V2= 235.1904761904762
Find square root
V= 15.3359211067
= 15.

Reach the ground at 15m s -¹


Note:
Formula To calculate kinetic energy:
Ek = 1/2 MV2
Ek= kinetic energy of an object
M= mass of object
V= velocity/speed of object

You might be interested in
6. The two ends of an iron rod are maintained at different temperatures. The amount of heat thatflows through the rod by conduct
motikmotik

Answer:

20cal/s

Explanation:

Question:

There are two questions. The first one has been answered:

From the formular, Power = Q/t = (kA∆T)/l

the amount heat depends on the duration of time interval, length of the iron rod, the thermal conductivity of iron and the temperature difference between the ends of the rod.

The amount of heat that flows through the rod by conduction during a given time interval does not depend upon the mass of the iron rod (D).

Second question:

The ends of a cylindrical steel rod are maintained at two different temperatures. The rod conducts heat from one end to the other at a rate of 10 cal/s. At what rate would a steel rod twice as long and twice the diameter conduct heat between the same two temperatures?

Solution:

Power = 10cal/s

Power = energy per unit time = Q/t

Where Q = energy

Power = (kA∆T)/l

k = thermal conductivity of iron

A = area

Area = πr^2

r = radius

Diameter = d = 2r

r = d/2

Area = (πd^2)/4

Length = l

∆T = change in temperature

10 = (kA∆T)/l

For a steel rod with length doubled and diameter doubled:

Let Length (L) = 2l

Diameter (D)= 2d

Area = π [(2d)^2]/4 = (π4d^2)/4

Area = 4(πd^2)/4

Using the formula Power = (kA∆T)/l, insert the new values for A and l

Power = [k × 4(πd^2)/4 × ∆T]/2l

Power = [4k((πd^2)/4) ∆T]/2l

Power = [(4/2)×k((πd^2)/4) ∆T]/l

Power = [2k(A) ×∆T]/l = 2(kA∆T)/l

Power of a steel that has its length doubled and diameter doubled = 2(kA∆T)/l

Recall initial Power = (kA∆T)/l = 10cal/s

And ∆T is the same

2[(kA∆T)/l] = 2 × 10

Power of a steel that has its length doubled and diameter doubled = 20cal/s

4 0
3 years ago
A computer is connected across a 110 V power supply. The computer dissipates 123 W of power in the form of electromagnetic radia
nexus9112 [7]

Answer:

81.3ohms

Explanation:

Resistance is known to provide opposition to the flow of electric current in an electric circuit.

Power dissipated by the computer is expressed as;

Power = current (I) × Voltage(V)

P = IV... (1)

Note that from ohms law, V = IR

I = V/R ... (2)

Substituting equation 2 into 1, we will have;

P = (V/R)×V

P = V²/R.. (3)

Given source voltage = 100V, Power dissipated = 123W

To get resistance R of the computer, we will substitute the given value into equation 3 to have

123 = 100²/R

R = 100²/123

R = 10,000/123

R = 81.3ohms

The resistance of the computer is 81.3ohms

3 0
3 years ago
Read 2 more answers
Boat A and Boat B have the same mass. Boat A's velocity is three times greater than that of Boat B. Compared to
Zarrin [17]

Answer:

nine times as much.

Explanation:

K.E of A = 9 times K.E of B

7 0
2 years ago
Read 2 more answers
Number of valence electrons for calcium?
zimovet [89]
Calcium has 2 valence electrons
7 0
3 years ago
Read 2 more answers
The atmosphere of Neptune and Uranus have a blue color because of which gas?
kirza4 [7]
They are blue because of hydrogen helium and methane
5 0
3 years ago
Other questions:
  • Consider a civilization broadcasting a signal with a power of 1.2×104 watts. The Arecibo radio telescope, which is about 300 met
    5·1 answer
  • When a force of 15 newtons is applied to a stationary chair, it starts moving. What can you say about the frictional force betwe
    15·1 answer
  • A large, cylindrical water tank with diameter 2.40 mm is on a platform 2.00 mm above the ground. The vertical tank is open to th
    5·1 answer
  • Which of the following astronomical bodies or collection of astronomical bodies is likely to be a part of the others listed?
    6·2 answers
  • What are 3 ways to say velocity is decreasing
    7·1 answer
  • Help please!!! Brainlyist to the person who answers and explains correctly!
    12·2 answers
  • Can someone plz check if what I typed is good :)
    12·1 answer
  • A rather devious student has built himself a slingshot, with the idea of firing
    5·1 answer
  • PLS ANWSER FAST WILL GIVE BRAINL!!!!
    5·1 answer
  • Which device uses electricity to produce a rotational motion? A computer C magnet B generator D motor​
    6·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!