Who said "give me a place to stand and a long enough lever and I can move the world"?

An apple from the top branch of the tree and an apple from the bottom branch of a tree fall at the same time. Which apple will h

Vedmedyk [2.9K]

B. The apple from the bottom will hit the ground earlier. This is because an increase in height causes an increase in the time that the object will fall, and therefore will affect the final velocity of the falling object. Moreover, the reduction in velocity due to friction from the air should also be considered.

3 0

2 years ago

One horse is pulling a 755 kg sled straight ahead applying a force of 1988 N. If the acceleration of the sled is 1.36 m/s2, what

Inessa [10]

Answer:

The coefficient of kinetic friction is 0.13

Explanation:

Newton's second law states that the acceleration of an object is proportional to the net force on it, the factor of proportionality is the mass. So, we can express that law mathematically as:

$\sum\overrightarrow{F}=m\overrightarrow{a}$ (1)

With F the net force, m the mass and a the acceleration of the object. In our case we're interested on what's happening to the sled, then we have to analyze the forces on it, those forces are the weight and the normal force on the vertical direction and the pulling force and frictional force in the horizontal direction. So, because (1) is a vector equation we can express that in their vertical (y) and horizontal (x) components:

$F_y=ma_y$ (2)

$F_x=ma_x$ (3)

On y we have that the acceleration is zero because the sled is not moving upward or downward, remember that the net force on y is the weight (W) pointing downward and the normal force pointing upward:

$F_y=W+n=0$

Following the convention that positive is upward and negative downward, W=mg=(755)(-9.81):

$F_y=(755)(-9.81)+n=0$

$n=7406.55 N$ (4)

Now on the x direction we have the sum of the forces is the pulling force (T) and friction force (f)

$F_x=F+f=ma_x$

Choosing the direction where the horse is pulling F=1988N and the acceleration should be positive too, then:

$1988+f=m(1.36)$

$f=(755)(1.36)-1988=-961.2 N$

The negative sign means it's in the opposite direction the horse is pulling

The frictional force is related with the coefficient of kinetic friction in the next way:

$|f|=\mu_k n$

with μk the coefficient of kinetic friction, and n the normal force that we already found on (4), so we simply solve the last equation for μk:

$\mu_k=\frac{|f|}{n}=\frac{961.2}{7406.55}=0.13$

4 0

3 years ago

James took two pea plants, placing one in a dark closet and the other on a sunny window sill. Both are located in air-conditione

Fudgin [204]

The constant is the temperature of the air that the plants get.

The independent variable is the thing that YOU control. That's the amount of sunlight each plant gets.

The <em>dependent variable</em> is anything that's caused by changes in the independent variable. That's the growth of the plants.

5 0

3 years ago

Read 2 more answers

Which equation relates charge, time, and current?

Ierofanga [76]

Answer:

I = Δq / t

Explanation:

The quantity of electricity i.e charge is related to current and time according to the equation equation:

Q = It

Δq = It

Where:

Q => is the quantity of electricity i.e charge

I => is the current.

t => is the time.

Thus, we can rearrange the above expression to make 'I' the subject. This is illustrated below:

Δq = It

Divide both side by t

I = Δq / t

6 0

2 years ago

Ann (mass 50 kg) is standing at the left end of a 15-m-long, 500 kg cart that has frictionless wheels and rolls on a frictionles

ivanzaharov [21]

Answer:

13.5 m

Explanation:

M = Mass of cart = 500 kg

m = Ann's mass = 50 kg

$v_m$ = Velocity of Ann relative to cart = 5 m/s

$v_M$ = Velocity of Cart relative to Ann

As the linear momentum of the system is conserved

$Mv_M+mv_m=0\\\Rightarrow v_M=-\frac{mv_m}{M}\\\Rightarrow v_M=-\frac{50\times 5}{500}\\\Rightarrow v_M=-0.5\ m/s$

Time taken to reach the right end by Ann

$Time=\frac{Distance}{Speed}\\\Rightarrow Time=\frac{15}{5}=3\ s$

Distance the cart will move in the 3 seconds

$Distance=Speed\times Time\\\Rightarrow Distance=-0.5\times 3=-1.5\ m$

The negative sign indicates opposite direction

Movement of Ann will be the sum of the distances

$15+(-1.5)=13.5\ m$

The net movement of Ann is 13.5 m

5 0

2 years ago