Is there any book for physics.

When an object is dropped from the top of a tall cliff, your teacher tells you to use -10 m/s2 for the approximate acceleration

Romashka-Z-Leto [24]

1. Answer: Option C

Displacement is a vector quantity. It has both magnitude as well as direction. Hence, it can be positive, zero or negative. In the given question, downward direction is taken as negative. This we have come to know from the downward acceleration $-10m/s^2$ . The negative sign indicates that downward direction is considered negative.

Now, since the object is dropped from the top. The displacement should be negative, because the negative represent a downward direction.

2. Answer: velocity

The truck is travelling at 30 mph to the west. From the unit mph (miles per hour), we know its a magnitude of velocity. West indicates the direction. Hence, the given quantity is a vector -velocity.

It is not speed because speed only indicates the magnitude and not the direction. speed is a scalar quantity.

3 0

3 years ago

Read 2 more answers

A) A spaceship passes you at a speed of 0.800c. You measure its length to be 31.2 m .How long would it be when at rest?

rosijanka [135]

Answer:

a

$l_o =52 \ m$

b

$l = 37.13 \ LY$

Explanation:

From the question we are told that

The speed of the spaceship is $v = 0.800c$

Here c is the speed of light with value $c = 3.0*10^{8} \ m/s$

The length is $l = 31.2 \ m$

The distance of the star for earth is $d = 145 \ light \ years$

The speed is $v_s = 2.90 *10^{8}$

Generally the from the length contraction equation we have that

$l = l_o \sqrt{1 -[\frac{v}{c } ]}$

Now the when at rest the length is $l_o$

So

$l_o =\frac{l}{\sqrt{ 1 - \frac{v^2}{c^2 } } }$

$l_o =\frac{ 31.2 }{ \sqrt{1 - \frac{(0.800c ) ^2}{c^2} } }$

$l_o=52 \ m$

Considering b

Applying above equation

$l =l_o \sqrt{1 - [\frac{v}{c } ]}$

Here $l_o =145 \ LY(light \ years )$

So

$l=145 * \sqrt{1 - \frac{v_s^2}{c^2 } }$

$l =145 * \sqrt{ 1 - \frac{2.9 *10^{8}}{3.0*10^{8}} }$

$l = 37.13 \ LY$

4 0

3 years ago

6. State whether each of the following is an example of conduction, convection, and/or radiation. Explain if you think there is

hodyreva [135]

A). Convection is heating the soup in the pot.
When you stick the spoon into the hot soup,
conduction heats the spoon all the way up to the end.

b). Water conducts heat a little bit.
But convection is much more responsible for the
uniform distribution of temperature in the kiddie pool.

c). The heat from the metal bench conducts directly
to the buttus epidermis when you sit on it.

d). You feel the heat on your face ... but not on the back of your
neck ... on account of radiation from the fire and the hot grill.

3 0

3 years ago

A drag racing car with a weight of 1600 lbf attains a speed of 270 mph in a quarter-mile race. Immediately after passing the tim

Kaylis [27]

Answer:

15.065ft

Explanation:

To solve this problem it is necessary to consider the aerodynamic concepts related to the Drag Force.

By definition the drag force is expressed as:

$F_D = -\frac{1}{2}\rho V^2 C_d A$