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Nesterboy [21]
3 years ago
8

A 40 kg skier starts at the top of a 12 meter high slope. At the bottom, she is traveling 10 miles. How much energy does she los

e to friction?
Physics
2 answers:
givi [52]3 years ago
8 0
Use conversion of energy. mgh+.5mv^2 initial = final. at the top there's no kinetic energy, at the bottom theres no potential. so mgh at the top=.5mv^2 at the bottom.
mgh at the top = 40 (9.8)(12)
not sure what you mean by 10 miles, do you mean 10 mph or 10 meters/second. if it isnt in SI units, do the proper conversions and put it in m/s
.5mv^2=.5 (40)(final velocity)
DaniilM [7]3 years ago
7 0
2,704 J i believe. Not sure
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A force of 14 N acts on a 5 kg object for 3 seconds.
DiKsa [7]

Answer: a) 42Nm b) 8.4m/s

Explanation:

Impulse is defined as object change in momentum.

Since Force = mass × acceleration

F = ma

Acceleration is the rate of change in velocity.

F = m(v-u)/t

Cross multiply

Ft = m(v-u)

Since impulse = Ft

and Ft = m(v-u)... (1)

The object change in velocity (v-u) = Ft/m from eqn 1

Going to the question;

a) Impulse = Force (F) × time(t)

Given force = 14N and time = 3seconds

Impulse = 14×3

Impulse = 42Nm

b) The object change in velocity (v-u) = Ft/m where mass = 5kg

v-u = 14×3/5

Change in velocity = 42/5 = 8.4m/s

3 0
3 years ago
A weightlifter works out at the gym each day. Part of her routine is to lie on her back and lift a 43 kg barbell straight up fro
Tasya [4]

Answer:

A. 231.77 J

B. 5330.71 J

C. 46 donuts

Explanation:

A. To lift the barbell once, she will have to extend it the full length of her arm. The work done will then be:

W = F * d

Where the force is the weight of the barbell.

F = m * g

Hence, the work done in lifting the barbell is:

W = m * g * d

W = 43 * 9.8 * 0.55

W = 231.77 J

B. If she does 23 repetitions, the total energy she expend will be equal to the Potential energy when the barbell is lifted multiplied by 23:

E = 23 * m * g * d

E = 23 * 231.77

E = 5330.71 J

C. 1 Joule = 4.184 calories

5330.71 Joules = 5330.71 * 4.184 = 22303.69

If 1 donut contains 490 calories, the number of donuts she will need will be:

N = 22303.69/490 = 45.5 donuts or 46 donuts

5 0
3 years ago
A certain spring stores 10.0J of potential energy when it isstretched by 2.00cm from its equilibrium position.How much potential
qaws [65]

Answer:

Answered

Explanation:

x= 0.02 m

E_p= 10.0 J

E_p= 0.5kx^2

10= 0.5k(0.02)^2

solving we get

K= 50.0 N/m

Now

E'_p= 0.5kx'^2

E'_p= 0.5×50×(0.04)^2

E'_p=40 J

b) potential energy is a scalar quantity and it only depends magnitude and not direction so it will remain same in compression and expansion both

c) 20 J = 0.5×50,000×x^2

solving

x= 0.028 m

d) k is 50.0 N/m  from above calculation

3 0
3 years ago
How much force does an 88kg astronaut exert on his chair while accelerating straight up at 10 m/s^2
Fed [463]
Force=mass*acceleration.         So 88kg*10 m/s^2=880 newtons
6 0
3 years ago
An airplane is heading due south at a speed of 430 km/h . A wind begins blowing from the northwest at a speed of 85.0 km/h (aver
Igoryamba

Answer:

It should fly 8° to west of south at 430km/h

Explanation:

According to the diagram. X components for both velocities must have the same magnitude in order to get the resultant velocity due south.

V_{w}*cos(45) = V_{A}*sin(\alpha )   Solving for α:

α = 8.03°

5 0
2 years ago
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