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CaHeK987 [17]
3 years ago
14

A 90 kg astronaut Travis is stranded in space at a point 12 m from his spaceship. In order to get back to his ship, Travis throw

s a 0.50 kg piece of equipment so that it moves at a speed of 4 m/ s directly away from the spaceship towards the left . How long will it take him to reach the ship? *hint find his speed after the collision and consider it a constant speed all the way back to his spaceship*
Physics
1 answer:
insens350 [35]3 years ago
7 0

Answer:

Explanation:

This is a recoil problem, which is just another application of the Law of Momentum Conservation. The equation for us is:

[m_av_a+m_ev_e]_b=[m_av_a+m_ev_e]_a which, in words, is

The momentum of the astronaut plus the momentum of the piece of equipment before the equipment is thrown has to be equal to the momentum of all that same stuff after the equipment is thrown. Filling in:

[(90.0)(0)+(.50)(0)]_b=[(90.0)(v)+(.50)(-4.0)]_a

Obviously, on the left side of the equation, nothing is moving so the whole left side equals 0. Doing the math on the right and paying specific attention to the sig fig's here (notice, I added a 0 after the 4 in the velocity value so our sig fig's are 2 instead of just 1. 1 is useless in most applications).

0 = 90.0v - 2.0 and

2.0 = 90.0v so

v = .022 m/s This is the rate at which he is moving TOWARDS the ship (negative was moving away from the ship, as indicated by the - in the problem). Now we can use the d = rt equation to find out how long this process will take him if he wants to reach his ship before he dies.

12 = .022t and

t = 550 seconds, which is the same thing as 9.2 minutes

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A car starts from rest and undergoes an acceleration of 4.0 m/s/s for a time of 5.0 s. What is the final velocity of the car?
Kruka [31]

Answer:

20m/s

Explanation:

acceleration=final velocity-initial velocity/time

4.0m/s²=v m/s-0m/s/5.0sec

5.0sec×4.0m/s²=v m/s-0m/s×5.0m/s/5.0m/s

20m/s=v

7 0
3 years ago
A 1400 kg car starts from rest on a horizontal road and gains a speed of 61 km/h in 19 s. (a) what is its kinetic energy at the
lana [24]
(a) Let's convert the final speed of the car in m/s:
v_f = 61 km/h = 16.9 m/s
The kinetic energy of the car at t=19 s is
K= \frac{1}{2}mv_f^2= \frac{1}{2}(1400 kg)(16.9 m/s)^2=2.00 \cdot 10^5 J

(b) The average power delivered by the engine of the car during the 19 s is equal to the work done by the engine divided by the time interval:
P= \frac{W}{\Delta t}
But the work done is equal to the increase in kinetic energy of the car, and since its initial kinetic energy is zero (because the car starts from rest), this translates into
P= \frac{K}{\Delta t}= \frac{2.00 \cdot 10^5 J}{19 s}=1.05 \cdot 10^4 W

(c) The instantaneous power is given by
P_i = Fv_f
where F is the force exerted by the engine, equal to F=ma.

So we need to find the acceleration first:
a= \frac{v_f-v_i}{\Delta t}=  \frac{16.9 m/s}{19 s}=0.89 m/s^2
And the problem says this acceleration is constant during the motion, so now we can calculate the instantaneous power at t=19 s:
P_i = Fv=(ma)v=(1400 kg)(0.89 m/s^2)(16.9 m/s)=2.11 \cdot 10^4 W
5 0
3 years ago
two workers are sliding 260 kg crate across the floor. one worker pushes forward on the crate with a force of 450 n while the ot
balu736 [363]

To find out the kinetic friction, using the coefficient friction formula.

What is kinetic friction?

A force that acts between moving surfaces is called "kinetic friction." A force acting in opposition to the direction of a moving body on the surface is felt. The two materials' kinetic friction coefficients will determine how much force is applied.

What is coefficient friction?

A measure of the degree of friction between two surfaces is the coefficient of friction. A coefficient of friction is determined by calculating the resistance to motion at the intersection of two surfaces made of the same or different materials.

UK

U-coefficient of friction

K-Kinetic friction

Using UK

450+370-f=m*o

f=820=UK*260*9.8

UK=2.548

820/2.548

UK= 321.8210361

Therefore the coefficient of kinetic friction is 321.8210361

Learn more about Kinetic friction from the given link.

brainly.com/question/14111192

#SPJ4

6 0
1 year ago
Net force is the sum of all the forces acting on an object. If a spring balance pulls on a body with a force of 10 N, and fricti
julsineya [31]

Answer:

5N

Explanation:

(25 N - 20 N = 5 N)

3 0
3 years ago
A small branch is wedged under a 200 kg rock and rests on a smaller object. The small object that creates a pivot point is calle
KiRa [710]

Answer:

F = 326.7 N

Explanation:

given data

mass m = 200 kg

distance d = 2 m

length L = 12 m

solution

we know force exerted by the weight of the rock that is

W = m × g   ..............1

W = 200 × 9.8

W = 1960 N

and

equilibrium the sum  of the moment about that is

∑Mf = F(cos∅) L - W (cos∅) d  = 0

here ∅ is very small so cos∅ L = L and cos∅ d = D

so F × L - W × d = 0       .................2

put here value

F × 12 - 1960 × 2 = 0

solve it we get

F = 326.7 N

8 0
3 years ago
Read 2 more answers
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