You are given two carts, a and

A 47.2 kg girl is standing on a 177 kg plank. The plank, originally at rest, is free to slide on a frozen lake, which is a flat,

Softa [21]

Answer:

v_g,i = 1.208 m/s

Explanation:

We are given;

Mass of girl; m_g = 47.2 kg

Mass of plank; m_p = 177 kg

Let the velocity of girl to ice be v_g,i

Let the velocity of plank to ice be v_p,i

Since the velocity of the girl is 1.53 m/s relative to the plank, then;

v_g,i + v_p,i = 1.53

From conservation of momentum;

m_g × v_g,i = m_p × v_p,i

Thus;

47.2(v_g,i) = 177(v_p,i)

Dividing both sides by 47.2 gives;

v_g,i = 3.75(v_p,i)

v_pi = (v_g,i)/3.75

Thus, from v_g,i + v_p,i = 1.53, we have;

v_g,i + ((v_g,i)/3.75) = 1.53

v_g,i(1 + 1/3.75) = 1.53

1.267v_g,i = 1.53

v_g,i = 1.53/1.267

v_g,i = 1.208 m/s

5 0

3 years ago

2. A student drives 7.8-km trip to school and averages a speed of

Alekssandra [29.7K]

Answer:

The total time is: t=451.22 sec

The average speed is: V=34.57 m/s

Explanation:

Average speed

The average speed is calculated by dividing the total distance traveled by an object (x) by the total time it took it to travel that distance (t).

$\displaystyle V=\frac{x}{t}$

Since the student makes the trip in two parts, we have to calculate the total distance and the total time.

We know the distance to school is 7.8 Km = 7,800 m. The student makes his way home over the same distance, thus the total distance is

x=2*7,800 m=15,600 m

The first trip to school was done at an average speed of v1=32.6 m/s. Knowing the distance and speed, we can calculate the time:

$\displaystyle t1=\frac{x1}{v1}=\frac{7,800}{32.6}=239.26\ sec$

The second trip back home was done at an average speed of v2=36.8 m/s. Let's calculate the second time:

$\displaystyle t2=\frac{x2}{v2}=\frac{7,800}{36.8}=211.96\ sec$

The total time is:

$t=239.26\ sec+211.96\ sec=451.22\ sec$

$\boxed{t=451.22\ sec}$

The average speed is:

$\displaystyle V=\frac{15,600}{451.22}=34.57\ m/s$

$\boxed{\displaystyle V=34.57\ m/s}$

6 0

3 years ago

A Ferris wheel turns at a constant 150.0 revolutions per hour. (a) Express this rate of rotation in units of radians per second.

RUDIKE [14]

Answer:

(a) 0.261 rad/s

(b) 1007.72 m

Explanation:

The angular velocity of the Ferris wheel is 150.0 revolutions per hour.

(a) To calculate the angular velocity of the wheel in units of radians per second, you take into account the following equivalence:

1 hour = 3600 seconds

1 revolution = 2π radians

You use the previous conversion factors:

$150.0\ \frac{rev}{h}*\frac{2\pi \ rad}{1\ rev}*\frac{1\ h}{3600\ s}=0.261\frac{rad}{s}$

In units of radians per seconds the wheel turns at 0.261 rad/s

(b) To find the arc length described by the wheel, you first calculate the angle described by the wheel in the time t, by using the following formula:

$\theta=\omega t$ (1)

ω: angular velocity = 0.261 rad/s

t: time = 4.95 min

You first convert the time to units of seconds

$4.95min*\frac{60s}{1min}=297s$

Next, you replace the values of the parameters in the equation (1):

$\theta=(0.261\frac{rad}{s})(297s)=77.51rad$

Next, you use the following formula for the arc length:

$s=r\theta$ (2)

r: radius of the wheel = 13.0 m

You replace the values of the parameters in the equation (2):

$s=(13.0m)(77.51rad)=1007.72m$

The arc length described by the wheel is 1007.72m

4 0

3 years ago

What do snow melting, water freezing to ice, and water boiling into steam have in

MissTica

Answer:

All of the above.

Explanation:

5 0

2 years ago

Read 2 more answers

If a car travels 80 miles between 2 and 4 pm, then its velocity is close to 40 mph at 2 pm.

Alisiya [41]

The answer should be false because it doesnt say if the car is traveling at constant speed. The cars speed can be various so that in total for 2 hours that it travels it passes 80 miles. If however it actually traveled at constant speed than the answer is true.

3 0

3 years ago