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
SIZIF [17.4K]
3 years ago
8

A girl is sledding down a slope that is inclined at 30º with respect to the horizontal. The wind is aiding the motion by providi

ng a steady force of 161 N that is parallel to the motion of the sled. The combined mass of the girl and the sled is 87.7 kg, and the coefficient of kinetic friction between the snow and the runners of the sled is 0.151. How much time is required for the sled to travel down a 271-m slope, starting from rest?

Physics
1 answer:
OleMash [197]3 years ago
8 0

Answer:

The sled required 9.96 s to travel down the slope.

Explanation:

Please, see the figure for a description of the problem. In red are the x and y-components of the gravity force (Fg). Since the y-component of Fg (Fgy) is of equal magnitude as Fn but in the opposite direction, both forces get canceled.

Then, the forces that cause the acceleration of the sled are the force of the wind (Fw), the friction force (Ff) and the x-component of the gravity force (Fgx).

The sum of all these forces make the sled move. Finding the resulting force will allow us to find the acceleration of the sled and, with it, we can find the time the sled travel.

The magnitude of the friction force is calculated as follows:

Ff = μ · Fn

where :

μ = coefficient of kinetic friction

Fn =  normal force

The normal force has the same magnitude as the y-component of the gravity force:

Fgy = Fg · cos 30º = m · g · cos 30º

Where

m = mass

g = acceleration due to gravity

Then:

Fgy = m · g · cos 30º = 87.7 kg · 9.8 m/s² · cos 30º

Fgy = 744 N

Then, the magnitude of Fn is also 744 N and the friction force will be:

Ff = μ · Fn = 0.151 · 744 N = 112 N

The x-component of Fg, Fgx, is calculated as follows:

Fgx = Fg · sin 30º = m·g · sin 30º = 87.7 kg · 9.8 m/s² · sin 30º = 430 N

The resulting force, Fr, will be the sum of all these forces:

Fw + Fgx - Ff = Fr

(Notice that forces are vectors and the direction of the friction force is opposite to the other forces, then, it has to be of opposite sign).

Fr = 161 N + 430 N - 112 N = 479 N

With this resulting force, we can calculate the acceleration of the sled:

F = m·a

where:

F = force

m = mass of the object

a = acceleration

Then:

F/m = a

a = 479N/87.7 kg = 5.46 m/s²

The equation for the position of an accelerated object moving in a straight line is as follows:

x = x0 + v0 · t + 1/2 · a · t²

where:

x = position at time t

x0 = initial position

v0 = initial velocity

t = time

a = acceleration

Since the sled starts from rest and the origin of the reference system is located where the sled starts sliding, x0 and v0 = 0.

x = 1/2· a ·t²

Let´s find the time at which the position of the sled is 271 m:

271 m = 1/2 · 5.46 m/s² · t²

2 · 271 m / 5.46 m/s² = t²

<u>t = 9.96 s </u>

The sled required almost 10 s to travel down the slope.

You might be interested in
Define Newton's third law:
Kisachek [45]

Answer:

the answer is B

Explanation:

the law states that for every action there is an equal and opposite reaction. action and reaction forces always act on two two different bodies and therefore THEY ALWAYS EXIST IN PAIRS.

3 0
2 years ago
Didn't know what type of science it was? But pls helpp
Alla [95]
The answer is the third one down. New evidence may contradict the old evidence of a certain theory.
8 0
3 years ago
Suppose you observed the equation for a traveling wave to be y(x, t) = A cos(kx − ????t), where its amplitude of oscillations wa
OLga [1]

Answer:

<h2>15m/s</h2>

Explanation:

The equation for a traveling wave as expressed as y(x, t) = A cos(kx − \omegat) where An is the amplitude f oscillation, \omega is the angular velocity and x is the horizontal displacement and y is the vertical displacement.

From the formula; k =\frac{2\pi x}{\lambda} \ and \ \omega = 2 \pi f where;

\lambda \ is\ the \ wavelength \ and\ f \ is\ the\ frequency

Before we can get the transverse speed, we need to get the frequency and the wavelength.

frequency = 1/period

Given period = 2/15 s

Frequency = \frac{1}{(2/15)}

frequency = 1 * 15/2

frequency f = 15/2 Hertz

Given wavelength \lambda = 2m

Transverse speed v = f \lambda

v = 15/2 * 2\\\\v = 30/2\\\\v = 15m/s

Hence, the transverse speed at that point is  15m/s

8 0
2 years ago
Explain how energy is transferred in an impact situation such as a car crash.
DaniilM [7]
During a car crash, energy is transferred from the vehicle to whatever it hits, be it another vehicle or a stationary object. ... The object that was struck will either absorb the energy thrust upon it or possibly transfer that energy back to the vehicle that struck it.

I HOPE THIS HELPSS???
Mark me brainliest
8 0
2 years ago
The storm surge of a hurricane can cause
BabaBlast [244]

Answer:

it can cause huricans and flooding

Explanation:

Storm surge is the rising of the sea level due to the low pressure, high winds, and high waves associated with a hurricane as it makes landfall. The storm surge can cause significant flooding and cost people their lives if they're caught unexpected

7 0
3 years ago
Read 2 more answers
Other questions:
  • Two bar magnets are labeled A and B. The ends of each magnet are numbered 1 or 2, but the poles are not labeled. When A1 is brou
    6·2 answers
  • A 35 g steel ball is held by a ceiling-mounted electromagnet 4.0 m above the floor. A compressed-air cannon sits on the floor, 4
    10·1 answer
  • A physics teacher performing an outdoor demonstration suddenly falls from rest off a high cliff and simultaneously shouts "Help.
    14·1 answer
  • What equation relates mechanical energy, thermal energy, and total energy when there is friction present in a system?
    11·1 answer
  • A girl of mass 55 kg throws a ball of mass 0.80 kg against a wall. The ball strikes the wall horizontally with a speed of 25 m/s
    7·2 answers
  • How many bottles of water should you drink in a week
    15·2 answers
  • A soccer ball is kicked horizontally and rolled off of a 30 meter high cliff. The soccer ball was kicked with a velocity of 17m/
    12·1 answer
  • In a series circuit, the current is _______
    14·2 answers
  • Dos cargas muy pequeñas de masas iguales m
    7·1 answer
  • 2.A girl of mass 50kg climbs a flight of a stair having 40steps each of 30m high in 10 s. Calculate the power developed by the g
    7·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!