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tatuchka [14]
3 years ago
9

A 55 kg roller skater is at rest on a flat skating rink, a 198 N horizontal force is needed to set the skater in motion.

Physics
1 answer:
Rufina [12.5K]3 years ago
8 0

Answer:

Explanation:

To get the person Moving you have to overcome the static (means not moving) friction coefficient.  U(static)

To get the person going at the same speed you have to overcome the kinetic friction coefficient. U(Kinetic)

Force to get him moving is 198 N.   Force = ma = U(static)Mg

combining the 2 equations you get 198N = U(static)* 55kg *9.8m/s^2   Solve for U(static)

Same equation to keep him moving except with the dynamic force and the dynamic U

 

175N=  U(kinetic)*55kg*9.8m/s^2  Solve (U dynamic)

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A car traveling at 27.4 m/s hits a bridge abutment. A passenger in the car, who has a mass of 65.0 kg, moves forward a distance
Minchanka [31]

Answer:

F=43570.9N

Explanation:

We can calculate the acceleration experimented by the passenger using the formula v_f^2=v_i^2+2ad, taking the initial direction of movement as the positive direction and considering it comes to a rest:

a=\frac{v_f^2-v_i^2}{2d}=\frac{-v_i^2}{2d}

Then we use Newton's 2nd Law to calculate the force the passenger of mass m experimented to have this acceleration:

F=ma=\frac{-mv_i^2}{2d}

Which for our values is:

F=\frac{-(65kg)(27.4m/s)^2}{2(0.56m)}=43570.9N

6 0
3 years ago
you add equal amounts of heat to two identical cylinders containing equal amounts of the same ideal gas. cylinder a is allowed t
OleMash [197]

Temperature rise will be there in cylinder B more than in cylinder A because of internal energy.

what is internal energy?

The sum of the kinetic and chemical potential energies of all the particles in the system is the internal energy. Particles accelerate and pick up kinetic energy when energy is applied to increase the temperature.

Briefing:

Cylinder A uses the heat it absorbs to both work while expanding and to increase internal energy (or temperature).

While cylinder B solely uses the heat it absorbs to increase its internal energy 

As a result, cylinder B's temperature rise is greater than cylinder A's.

To know more about internal energy visit:

brainly.com/question/11278589

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3 0
1 year ago
Batman (mass = 96.1 kg) jumps straight down from a bridge into a boat (mass = 458 kg) in which a criminal is fleeing. The veloci
MariettaO [177]

Answer:

The velocity of the boat after the batman lands in it is +9.26 m/s

Explanation:

Applying the law of conservation of momentum,

Total momentum before collision = Total momentum after collision.

Note: The collision between the Batman and the boat is an inelastic collision.

m'u'+mu = V(m+m').................... Equation 1

Where m' = mass of the Batman, u' = initial velcoity of the batman, m = mass of the boat, u = initial velocity of the boat, V = common velocity.

make V the subject of equation 1

V = (m'u'+mu)/(m+m')............... Equation 2

Given: m' = 96.1 kg, u' = 0 m/s, m = 458 kg, u = +11.3 m/s.

Substitute these values into equation 2

V = [(96.1×0)+(458×11.2)]/(96.1+458)

V = 5129.6/554.1

V = +9.26 m/s

8 0
3 years ago
A fireperson is 50 m from a burning building and directs a stream of water from a fire hose at an angle of 300 above the horizon
notsponge [240]

Answer:

We can think the water stream as a solid object that is fired.

The distance between the fireperson and the building is 50m. (i consider that the position of the fireperson is our position = 0)

The angle is 30 above the horizontal. (yo wrote 300, but this has no sense because 300° implies that he is pointing to the ground).

The initial speed of the stream is 40m/s.

First, using the fact that:

x = R*cos(θ)

y = R*sin(θ)

in this case R = 40m/s and θ = 30°

We can use the above relation to find the components of the velocity:

Vx = 40m/s*cos(30°) = 34.64m/s

Vy = 20m/s.

First step:

We want to find the time needed to the stream to hit the buildin.

The horizontal speed is 34.64m/s and the distance to the wall is 50m

So we want that:

34.64m/s*t = 50m

t = 50m/(34.64m/s) = 1.44 seconds.

Now we need to calculate the height of the stream at t = 1.44s

Second step:

The only force acting on the water is the gravitational one, so the acceleration of the stream is:

a(t) = -g.

g = -9.8m/s^2

For the speed, we integrate over time and we get:

v(t) = -g*t + v0

where v0 is the initial speed: v0 = 20m/s.

The velocity equation is:

v(t) = -g*t + 20m/s.

For the position, we integrate again over time:

p(t) = -(1/2)*g*t^2 + 20m/s*t + p0

p0 is the initial height of the stream, this data is not known.

Now, the height at the time t = 1.44s is

p(1.44s) = -5.9m/s^2*(1.44s)^2 + 20m/s*1.44s + po

             = 16.57m + p0

So the height at wich the stream hits the building is 16.57 meters above the initial height of the fire hose.

5 0
3 years ago
an object starts from rest with a constant acceleration of 8.0m/s^2 along a straight line.find the average speed for 5 second in
frozen [14]

Answer:

40 m/s

Explanation:

If you multiply the acceleration with time you get the average speed.

6 0
2 years ago
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