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
sesenic [268]
3 years ago
8

A dynamite blast at a quarry launches a rock straight upward, and 1.7 s later it is rising at a rate of 17 m/s. Assuming air res

istance has no effect on the rock, calculate its speed (a) at launch and (b) 4.9 s after launch.
Physics
1 answer:
Shtirlitz [24]3 years ago
3 0

Answer:

(a) v_0= 34m/s

(b) v=14m/s

Explanation:

We can derive the initial speed of the rock from the equation of the speed in function of the time:

v=v_0-gt\\\\\implies v_0=v+gt

Using the given values for the speed at time t=1.7s, we get:

v_0=17m/s+(9.8m/s^{2})(1.7s)=34m/s

In words, the speed of the rock at launch is 34m/s (a).

Next, we use this to calculate the speed at t=4.9s:

v=v_0-gt\\\\v= 34m/s-(9.8m/s^{2})(4.9s)=-14m/s

This means that the speed of the rock at 4.9s after the launch is 14m/s (b), and the negative sign means that it is moving downwards.

You might be interested in
A stone is dropped into a lake, creating a circular ripple that travels outward at a speed of 50 cm/s. Find the rate at which th
Drupady [299]
The radius of the circle, in cm, after t seconds would be 50t 
The area, A, of the circle after t seconds is expressed in the equation: A = pi * r^2 
A = pi * (50T)^2 = pi*2500*t^2 
The change of area per unit time is obtained by differentiating the equation
A' = pi*2500*2*t A' = pi*5000*t
when t = 3 secondsA' = pi*5000*3 = 47122 cm2/s
6 0
3 years ago
A long coaxial cable consists of an inner cylindrical conductor with radius a and an outer coaxial cylinder with inner radius b
Natasha_Volkova [10]

Answer:

Part a)

E = \frac{\lambda}{2\pi \epsilon_0 r}

Part b)

E = \frac{\lambda}{2\pi \epsilon_0 r}

Part d)

As we know that due to induction of charge there will be same charge appear on the inner and outer surface of the cylinder but the sign of the charge must be different

On the inner side of the cylinder there will be negative charge induce on the inner surface and on the outer surface of the cylinder there will be same magnitude charge with positive sign.

Explanation:

Part a)

By Guass law we know that

\int E. dA = \frac{q}{\epsilon_0}

E. 2\pi rL = \frac{\lambda L}{\epsilon_0}

E = \frac{\lambda}{2\pi \epsilon_0 r}

Part b)

Outside the outer cylinder we will again use Guass law

\int E. dA = \frac{q}{\epsilon_0}

E. 2\pi rL = \frac{\lambda L}{\epsilon_0}

E = \frac{\lambda}{2\pi \epsilon_0 r}

Part d)

As we know that due to induction of charge there will be same charge appear on the inner and outer surface of the cylinder but the sign of the charge must be different

On the inner side of the cylinder there will be negative charge induce on the inner surface and on the outer surface of the cylinder there will be same magnitude charge with positive sign.

4 0
3 years ago
Help me with the question in the image I provided​
inna [77]

Answer: 10 s, 30 m/s , 150 m

Explanation:

Given

The speed of motorcyclist is  u_1=15\ m/s

The initial speed of a police motorcycle is u_2=0\ m/s

acceleration of police motorcycle is a=3\ m/s^2

Police will catch the motorcyclist when they traveled equal distances

distance traveled by motorcyclist in time t is

\Rightarrow s_1=15\times t

Distance traveled by Police in time t is

\Rightarrow s_2=u_2t+\frac{1}{2}at^2\\\Rightarrow s_2=0+0.5\times 3\times t^2

put s_1=s_2

\Rightarrow 15t=0.5\times 3\times t^2\\\\\Rightarrow t(1.5t-15)=0\\\\\Rightarrow t=\dfrac{15}{1.5}=10\ s

Police officer's speed at that time is

\Rightarrow v_2=u_2+at\\\Rightarrow v_2=0+3\times 10=30\ m/s

Distance traveled by each vehicle is

\Rightarrow s_1=s_2=15\times t=15\times 10=150\ m

8 0
3 years ago
The downsprue leading into the runner of a certain mold has a length of 175 mm. The cross-sectional area at the base of the spru
adoni [48]

Answer:

(a) Velocity at bottom is 1.85 m/s

(b) Volume flow rate is 7.4 x 10⁻⁴ m³/s.

(c) The time required to fill the mold is 1.35 s.

Explanation:

(a)

Applying Bernoulli's Equation on both ends of the down sprue, with the assumptions that every point is at atmospheric pressure and the liquid metal at the pouring basin is at zero velocity. The equation then becomes:

V = √2gh

where,

V = velocity at bottom of down sprue

h = height of down sprue = 175 mm = 0.175 m

V = √2(9.8 m/s²)(0.175 m)

<u>V = 1.85 m/s</u>

<u></u>

(b)

The volume flow rate is given as:

Volume Flow Rate = (V)(A)

where,

V = velocity at bottom = 1.85 m/s

A = Area of bottom = 400 mm² = 0.0004 m²

Therefore,

Volume Flow Rate = (1.85 m/s)(0.0004 m²)

<u>Volume Flow Rate = 7.4 x 10⁻⁴ m³/s = 740 cm³/s</u>

(c)

The time required to fill the cavity is given as:

Volume Flow Rate = V/t

where,

V = Volume of mold Cavity = 0.001 m³

t = time required to fill the cavity = ?

Therefore,

t = V/Volume Flow Rate

t = 0.001 m³/7.4 x 10⁻⁴ m³/s

<u>t = 1.35 s</u>

<u></u>

5 0
3 years ago
A 562 N trunk is on frictionless plane inclined at 30.0 degrees from the horizontal. What is the acceleration of the trunk down
Len [333]

Answer: 0m/s²

Explanation:

Since the forces acting along the plane are frictional force(Ff) and moving force(Fm), we will take the sum of the forces along the plane

According newton's law of motion

Summation of forces along the plane = mass × acceleration

Frictional force is always acting upwards the plane since the body will always tends to slide downwards on an inclined plane and the moving acts down the plane

Ff = nR where

n is coefficient of friction = tan(theta)

R is normal reaction = Wcos(theta)

Fm = Wsin(theta)

Substituting in the formula of newton's first law we have;

Fm-Ff = ma

Wsin(theta) - nR = ma

Wsin(theta) - n(Wcos(theta)) = ma... 1

Given

W = 562N, theta = 30°, n = tan30°, m = 56.2kg

Substituting in eqn 1,

562sin30° - tan30°(562cos30°) = 56.2a

281 - 281 = 56.2a

0 = 56.2a

a = 0m/s²

This shows that the trunk is not accelerating

4 0
3 years ago
Other questions:
  • A bicycle rider travels 50.0 km in 2.5 hours what is te bicyclist average speed
    8·2 answers
  • 50POINTS! What is the escape velocity for lunar module? Lunar module mass 15,200 kg radius of moon 1.74x106m, mass of moon 7.34x
    8·2 answers
  • Star x has twice the mass of the sun
    12·1 answer
  • A team of students conducts a series of experiments to investigate collisions. In the first experiment, the two carts collide wi
    13·1 answer
  • 1.) What is the equation for Average Speed?
    10·2 answers
  • What particular appropriate program/application is installed on the system where in the user can utilize and browse educational
    12·1 answer
  • determine the longest wavelength of light required to remove an electron from a sample of potassium metal, if the binding energy
    9·1 answer
  • What do ethical guidelines for research with human subjects mean?
    6·1 answer
  • A body is projected vertically upwards with a speed 100 m/s from the ground then distance it covers in its last second of its up
    15·1 answer
  • Given a circuit consisting of a DC battery of voltage 200 volts connected to a single resistor. If the electric current through
    6·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!