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3 years ago

A girl is sitting in a sled sliding horizontally along some snow (there is friction present).

Physics

1 answer:

Over [174]3 years ago

4 0

Answer:

159 N

Explanation:

The force of friction, Fr is a product of coefficient of feiction and the normal force. Therefore, Fr=uN where N is the normal force and u is coefficient of friction. Here, we have two coefficients of friction but since it is sliding, then we use coefficient of kinetic energy. Substituting 0.25 for u and 636 N for N then

Fr=0.25*636=159 N

Therefore, the force of friction is equivalent to 159 N

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Two students are on a balcony 19.1 m above the street. One student throws a ball, b1, vertically downward at 13.9 m/s. At the sa

tester [92]

Answer:

Part a)

$t = 2.83 s$

Part b)

Ball thrown downwards = $v_f = 23.8 m/s$

Ball thrown upwards = $v_f = 23.8 m/s$

Part c)

$d = 22.24 m$

Explanation:

Part a)

Since both the balls are projected with same speed in opposite directions

So here the time difference is the time for which the ball projected upward will move up and come back at the same point of projection

Afterwards the motion will be same as the first ball which is projected downwards

so here the time difference is given as

$\Delta y = 0 = v_y t + \frac{1}{2}at^2$

$0 = 13.9 t - \frac{1}{2}(9.81) t^2$

$t = 2.83 s$

Part b)

Since the displacement in y direction for two balls is same as well as the the initial speed is also same so final speed is also same for both the balls

so it is given as

$v_f^2 - v_i^2 = 2 a \Delta y$

$v_f^2 - (13.9)^2 = (2)(-9.81)(-19.1)$

$v_f^2 = 567.9$

$v_f = 23.8 m/s$

Part c)

Relative speed of two balls is given as

$v_{12} = v_1 - v_2$

$v_{12} = (13.9) - (-13.9) = 27.8 m/s$

now the distance between two balls in 0.8 s is given as

$d = v_{12} t$

$d = 27.8 \times 0.8$

$d = 22.24 m$

7 0

4 years ago

A motorcycle rider moving with an initial velocity of 9.2 m/s uniformly accelerates to a speed of 19.1 m/s in a distance of 32.0

Vlada [557]

Acceleration = (final velocity^2 - initial velocity^2) / 2 * distance

Acceleration = (19.1^2 - 9.2^2) / 2 * 32

Acceleration = (364.81 - 84.64) / 64

Acceleration = 280.17 / 64

Acceleration = 4.3777m/s^2

:)

6 0

3 years ago

Can someone plz help me with this

Elena-2011 [213]

1st Law: Objects that are in motion tend to stay in motion. This motion can change with external forces.

If you were to stop pedaling on bike while in motion, you will notice that you will keep moving. This is because a moving body (you) has inertia. If there wasn't any friction between the tires and the ground, between the axles and wheel, any air resistance, or any other force that acts against you, then you could be coasting indefinitely! 

2nd Law: Force is equal to the mass times acceleration. 

When you pedal, you are applying a force onto the pedal. This force is then translated through tension to apply torque onto the wheel. Turning the wheel will make you accelerate in the lateral direction. 

3rd Law: For every action, there is an equal and opposite reaction. 

Without this, you could pedal and pedal, but you will be not go anywhere! It is essentially the friction between the tires and the ground that propels you forward. If the ground did not apply to the tire the same amount of force that the tire was applying to the ground, the tire would not "catch" and no friction would be applied. And if there was no third law, the weight of you and your bike would "sink" into the ground because the ground would not be applying a normal force back onto you.

hope this helps and if you have any questions just hmu and ask :)

3 0

3 years ago

Which statement best describes how electric fields and magnetic fields are alike?

gladu [14]

Electric field repulsive for objects of like charge and attractive for opposite type of charges and for a magnet you can say that like poles repel and unlike attracts so D makes sense

3 0

3 years ago

As streams flow through Stone Mountain, layers of sand build up. Over time, the sand particles form a sedimentary rock called sa

Firlakuza [10]

As streams flow through Stone Mountain, layers of sand build up. Over time, the sand particles form a sedimentary rock called sandstone. What causes sandstone to change into metamorphic rock at Stone Mountain? Sandstone experiences intense heat and pressure.

(Correct Answer is above)

Also Mark Brainliest please.

3 0

4 years ago

Read 2 more answers