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
Digiron [165]
3 years ago
14

A small grinding wheel is attached to the shaft of an electric motor which has a rated speed of 3600 rpm. When the power is turn

ed on, the unit reaches its rated speed in 5 s, and when the power is turned off, the unit coasts to rest in 70 s. Assuming uniformly accelerated motion, determine the number of revolutions that the motor executes (a) in reaching its rated speed, (b) in coasting to rest.
Physics
1 answer:
dolphi86 [110]3 years ago
6 0

Answer:

(a) θ1 = 942.5rad, (b) θ2 = 13195 rad

Explanation:

(a) Given

ωo = 0 rad/s

ω = 3600rev/min = 3600×2(pi)/60 rad/s

ω = 377rad/s

t1 = 5s

θ1 = (ω + ωo)t/2

θ1 = (377 +0)×5/2

θ1 = 942.5 rads

(b) ωo = 377rad/s

ω = 0 rad/s

t2 = 70s

θ2 = (ω + ωo)t/2

θ2 = (377 +0)×70/2

θ2 = 13195 rad

You might be interested in
a flag of mass 2.5 kg is supported by a single rope. A strong horizontal wind exerts a force of 12 N on the flag. Calculate the
tatuchka [14]
The free-body diagram of the forces acting on the flag is in the picture in attachment.

We have: the weight, downward, with magnitude
W=mg = (2.5 kg)(9.81 m/s^2)=24.5 N
the force of the wind F, acting horizontally, with intensity
F=12 N
and the tension T of the rope. To write the conditions of equilibrium, we must decompose T on both x- and y-axis (x-axis is taken horizontally whil y-axis is taken vertically):
T \cos \alpha -F=0
T \sin \alpha -W=
By dividing the second equation by the first one, we get
\tan \alpha =  \frac{W}{F}= \frac{24.5 N}{12 N}=2.04
From which we find
\alpha = 63.8 ^{\circ}
which is the angle of the rope with respect to the horizontal.

By replacing this value into the first equation, we can also find the tension of the rope:
T= \frac{F}{\cos \alpha}= \frac{12 N}{\cos 63.8^{\circ}}=27.2 N




7 0
3 years ago
You drop a ball at 27 feet high. How long will it take for the ball to hit the ground?
ivolga24 [154]

Ball will hit the ground after a time of 1.296 s

Explanation:

initial velocity of ball= Vi=0

g= 9.8 m/s²

height =h= 27 ft=8.23 m

using the kinematic equation

h= Vi t + 1/2 gt²

8.23=0(t) + 1/2 (9.8)t²

t²=1.6796

t=1.296 s

6 0
3 years ago
Một người đi đều với vận tốc 1,5 m/s, muốn đi quãng đường dài 1,5 km thì người
andrezito [222]
T=s/v=>t=1500/1,5=1000s
1,5km=1500m
6 0
2 years ago
Two forces F1 and F2 are acting on the box shown in the drawing, causing the box to move across the floor. The two force vectors
SpyIntel [72]

Answer: The correct answer is (b) F1 does more work than F2.

The block is moving horizontally the direction is opposite to direction of motion. The two forces applied are F1 and F2.F1 is applied horizontally so its horizontal component is F1cos0 = F1

While F2 is at angle  so horizontal component of F2 is F2cos(theta) and as we know cos is a decreasing in 0 to 90 degree. Therefore F1 does more work than F2.

Work is defined as the product of the magnitude of a force and the displacement of the object it is acting upon. In this case, the forces F1 and F2 are acting on the box, causing it to move across the floor. To calculate the work done by each force, we need to calculate the magnitude of the force and the displacement of the box.

The magnitude of F1 is given in the diagram, and it is 2 N. The magnitude of F2 is also given, and it is 4 N. For the displacement of the box, we will assume it is 1 m.

Now we can use the formula W = F x d to calculate the work done by each force.

For F1: W1 = 2 N x 1 m = 2 J

For F2: W2 = 4 N x 1 m = 4 J

Since F1 does 2 J of work, and F2 does 4 J of work, F1 does more work than F2 does. Therefore, the correct answer is (b) F1 does more work than F2 does.

Find More: https://brainly.in/question/17901995?referrer=searchResults

#SPJ4

7 0
1 year ago
A child pulls a wagon with a force F at an angle o with respect to the horizontal. Which of the following free body diagrams is
NeTakaya

Option d) is the correct free body diagram.

Explanation:

A free-body diagram is a diagram that shows all the forces acting on a body. Each force is represented using an arrow, where:

- The length of the arrow is proportional to the magnitude of the force

- The direction of the arrow corresponds to the direction of the force

For the block in this problem, we have the following forces:

- The force F applied from the child, which acts at an angle with respect to the horizontal --> this rules out option a) and c), where the force acts horizontally

- The force of gravity (the weight of the object), labelled with W, which always acts downward --> this rules out option b), since the weight acts downward.

Therefore, the correct option is d).

(in reality, there should be another force: the normal reaction exerted by the floor on the block, N, acting upward).

Learn more about forces and weight:

brainly.com/question/8459017

brainly.com/question/11292757

brainly.com/question/12978926

#LearnwithBrainly

5 0
3 years ago
Other questions:
  • 10 m/s2 to km/h2 help<br>​
    12·2 answers
  • Difference between male and female gamete​
    9·2 answers
  • Which of the following is a vector quantity?
    14·2 answers
  • Read the scientific question below.
    5·2 answers
  • When a voltage difference is applied to a piece of metal wire, a 10.0 mA current flows through it. If this metal wire is now rep
    14·1 answer
  • You could use an elevator or the stairs to lift a box to tenth floor.which has greater power?
    12·1 answer
  • A tennis ball moves 16 meters northward, then 22 meters southward, then 12 meters northward, and finally 32 meters southward.
    6·1 answer
  • A pilot drops a bomb from a plane flying horizontally. Where will the plane be located when the bomb hits the ground
    8·1 answer
  • (PLEASE answer ASAP, Will give brainliest)
    15·1 answer
  • A tennis ball is dropped from a height of 3 m and bounces back to a height of
    12·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!