Answer:
a = 4.05 m/s²
Explanation:
Known data
m= 92 kg : mass of the skier
θ =30° :angle θ of the ski slope with respect to the horizontal direction
μk= 0.10 : coefficient of kinetic friction
g = 9.8 m/s² : acceleration due to gravity
Newton's second law:
∑F = m*a Formula (1)
∑F : algebraic sum of the forces in Newton (N)
m : mass s (kg)
a : acceleration (m/s²)
We define the x-axis in the direction parallel to the movement of the block on the ramp and the y-axis in the direction perpendicular to it.
Forces acting on the skier
W: Weight of the skier : In vertical direction
N : Normal force : perpendicular to the ski slope
f : Friction force: parallel to the ski slope
Calculated of the W
W= m*g
W= 92kg* 9.8 m/s² = 901,6 N
x-y weight components
Wx= Wsin θ= 901,6 N
*sin 30° = 450.8 N
Wy= Wcos θ = 901,6 N
*cos 30° =780.8 N
Calculated of the N
We apply the formula (1)
∑Fy = m*ay ay = 0
N - Wy = 0
N = Wy
N = 780.8 N
Calculated of the f
f = μk* N= 0.10*780.8 N
f = 78.08 N
We apply the formula (1) to calculated acceleration of the skier:
∑Fx = m*ax , ax= a : acceleration of the block
Wx - f = m*a
450.8- 78.08 = ( 92)*a
372.72 = (92)*a
a = (372.72)/ (92)
a = 4.05 m/s²
Answer:
coasting down hill on a bicycle
Explanation:
Coasting down the hill on a bicycle is a typical example of how kinetic energy is being transformed to potential energy in a system.
Kinetic energy is the energy due to the motion of a body, it can be derived using the expression below;
K.E = 
m v²
Potential energy is the energy due to the position of a body. It can be derived using;
P.E = mgh
m is the mass
v is the velocity
g is the acceleration due to gravity
h is the height
Now, at the top of the hill, the potential energy is at the maximum. As the bicycle coasts down the potential energy is converted to kinetic energy.
Impulse = (force) x (length of time the force lasts)
I see where you doodled (60)(40) over on the side, and you'll be delighted
to know that you're on the right track !
Here's the mind-blower, which I'll bet you never thought of:
On a force-time graph, impulse (also change in momentum)
is just the <em>area that's added under the graph during some time</em> !
From zero to 60, the impulse is just the area of that right triangle
under the graph. The base of the triangle is 60 seconds. The
height of the triangle is 40N . The area of the triangle is not
the whole (base x height), but only <em><u>1/2 </u></em>(base x height).
1/2 (base x height) = 1/2 (60s x 40N) = <u>1,200 newton-seconds</u>
<u>That's</u> the impulse during the first 60 seconds. It's also the change in
the car's momentum during the first 60 seconds.
Momentum = (mass) x (speed)
If the car wasn't moving at all when the graph began, then its momentum is 1,200 newton-sec after 60 seconds. Through the convenience of the SI system of units, 1,200 newton-sec is exactly the same thing as 1,200 kg-m/s . The car's mass is 3 kg, so after 60 sec, you can write
Momentum = M x V = (3 kg) x (speed) = 1,200 kg-m/s
and the car's speed falls right out of that.
From 60to 120 sec, the change in momentum is the added area of that
extra right triangle on top ... it's 60sec wide and only 20N high. Calculate
its area, that's the additional impulse in the 2nd minute, which is also the
increase in momentum, and that'll give you the change in speed.
Changing frequency of sound does not change the speed of the sound.
Explanation:
- Speed of the sound gets altered when the sound travels from one medium to another.
- Change in frequency does not affect the speed of the sound and speed is affected by the properties of the medium through which it travels.
- Therefore, to change the speed of the sound, the properties of the medium needs to be changed.
