Which of the following is defined as displacement over change in time?

A giant log float on a lake while a tiny grain of sand sinks to the bathroom. Explain why a heavy object like the log floats whi

ella [17]

Answer:

Because the log is hollow or is less dense

Explanation:

If a log has little density, it will float. While sand is dense and completely solid, so it will sink.

7 0

2 years ago

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43. A rocket sled accelerates at a rate of 49.0m/s2. Its passenger has a mass of 75.0 kg. (a) Calculate the horizontal component

lord [1]

(a) 3675 N

Assuming that the acceleration of the rocket is in the horizontal direction, we can use Newton's second law to solve this part:

$F_x = m a_x$

where

$F_x$ is the horizontal component of the force

m is the mass of the passenger

$a_x$ is the horizontal component of the acceleration

Here we have

m = 75.0 kg

$a_x = 49.0 m/s^2$

Substituting,

$F_x=(75.0)(49.0)=3675 N$

(b) 3748 N, 11.3 degrees above horizontal

In this part, we also have to take into account the forces acting along the vertical direction. In fact, the seat exerts a reaction force (R) which is equal in magnitude and opposite in direction to the weight of the passenger:

$R=mg=(75.0)(9.8)=735 N$

where we used

$g=9.8 m/s^2$ as acceleration of gravity.

So, this is the vertical component of the force exerted by the seat on the passenger:

$F_y = 735 N$

and therefore the magnitude of the net force is

$F=\sqrt{F_x^2+F_y^2}=\sqrt{3675^2+735^2}=3748 N$

And the direction is given by

$\theta = tan^{-1}(\frac{F_y}{F_x})=tan^{-1}(\frac{735}{3675})=11.3^{\circ}$

4 0

3 years ago

During a race, a runner runs at a speed of 6 m/s. 2 seconds later, she is running at a speed of 10 m/s. What is the runner’s acc

Lina20 [59]

V o = 6 m/s,
t = 2 s
v = 10 m/s
v = v o + a t
a t = v - v o
a = ( v - v o ) / t
a = ( 10 m/s - 6 m/s ) / 2 s = 4 m/s / 2 s = 2 m/s²
Answer:
The runner`s acceleration is 2 m/s².

6 0

3 years ago

Earth's gravity accelerates objects at 9.8 m/s2. When the flying object reaches the top of its arc (even if it is not pictured),

otez555 [7]

The motion of falling objects is the simplest and most common example of motion with changing velocity. The early pioneers of physics had a correct intuition that the way things drop was a message directly from Nature herself about how the universe worked. Other examples seem less likely to have deep significance. A walking person who speeds up is making a conscious choice. If one stretch of a river flows more rapidly than another, it may be only because the channel is narrower there, which is just an accident of the local geography. But there is something impressively consistent, universal, and inexorable about the way things fall.

3 0

3 years ago

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A ball moves along a smooth metal surface while an identical ball moves along concrete.

mojhsa [17]

Answer:

2. The metal surface exerts less frictional force because there are fewer bumps and irregularities on it than there are on the concrete.

Explanation:

Frictional force is a force that is exerted between two surfaces in contact with each other. Frictional force always opposes the direction of relative motion of the two surfaces: for instance, for a ball moving along a surface, the force of friction exerted by the surface on the ball points opposite to the direction of motion of the ball.

The magnitude of the frictional force for a ball moving on a flat surface is given by

$F=\mu mg$

where

$\mu$ is the coefficient of friction

m is the mass of the ball

g is the acceleration of gravity

The value of $\mu$ depends on the type of surface involved. In particular, a smooth surface has a smaller value of $\mu$ , while a rough surface will have a bigger value. In this case, we are comparing a smooth metal surface with concrete: since the metal surface has fewer bumps and irregularities than concrete, it has a smaller value of coefficient of friction, so it exerts less frictional force than concrete.

3 0

3 years ago