A wave has a frequency of 12 Hz and a wavelength of 5 m. What is the wave speed?

The 10-kg block is held at rest on the smooth inclined plane by the stop block at A. If the10-g bullet is traveling at 300m/swhe

WARRIOR [948]

Answer:

6.8 mm

Explanation:

We are given that

Mass of block,m=10 kg

Mass of bullet, $m_b=10 g=10\times 10^{-3} kg$

1 kg=1000 g

Total mass of system,M= $m+m_a=10+10\times 10^{-3}=10.01kg$

Speed of bullet,u=300 m/s

$\theta=30^{\circ}$

By law of conservation of momentum

$m_bucos\theta=Mv$

$v=\frac{m_bvcos\theta}{M}=\frac{0.01\times 300cos30^{\circ}}{10.01}=0.259m/s$

According to law of conservation of energy

Change in kinetic energy of system=Change in potential energy of system

$\frac{1}{2}Mv^2-0=Mgh-0$

$\frac{1}{2}(10.01)(0.259)^2=10.01\times 9.8 h$

Where $g=9.8 m/s^2$

$h=\frac{(0.259)^2}{2\times 9.8}=0.0034m$

1m=100 cm

$h=0.0034\times 100=0.34 cm$

Distance traveled by block= $d=\frac{h}{sin\theta}=\frac{0.34}{sin30^{\circ}}=0.68 cm=6.8 mm$

1cm=10 mm

4 0

4 years ago

A boy im50kg at rest on a skateboard is pushed by another boy who exerts a force of 200 N on him. If the first boy's

sergey [27]

Answer:

Time, t = 2 seconds

Explanation:

Given the following data;

Mass, m = 50 kg

Initial velocity, u = 0 m/s (since it's starting from rest).

Final velocity, v = 8 m/s

Force, F = 200 N

To find the time, we would use the following formula;

$F = \frac {m(v - u)}{t}$

Making time, t the subject of formula, we have;

$t = \frac {m(v - u)}{F}$

Substituting into the formula, we have;

$t = \frac {50(8 - 0)}{200}$

$t = \frac {50*(8)}{200}$

$t = \frac {400}{200}$

Time, t = 2 seconds

5 0

3 years ago

A ball is thrown down vertically with an initial speed of 20 m/s from a height of 60 m. Find (a) its speed just before it strike

vivado [14]

Answer:

Explanation:

Ball is thrown downward:

initial velocity, u = - 20 m/s (downward)

height, h = - 60 m

Acceleration due to gravity, g = - 9.8 m/s^2 (downward)

(a) Let the speed of the ball as it hits the ground is v.

Use third equation of motion

$v^{2}=u^{2}+2as$

$v^{2}=(-20)^{2}+2\times 9.8 \times 60$

v = 39.69 m/s

(b) Let t be the time taken

Use First equation of motion

v = u + a t

- 39.69 = - 20 - 9.8 t

t = 2 second

Now the ball is thrown upwards:

initial velocity, u = 20 m/s (upward)

height, h = - 60 m

Acceleration due to gravity, g = - 9.8 m/s^2 (downward)

(c) Let the speed of the ball as it hits the ground is v.

Use third equation of motion

$v^{2}=u^{2}+2as$

$v^{2}=(-20)^{2}+2\times 9.8 \times 60$

v = 39.69 m/s

(d) Let t be the time taken

Use First equation of motion

v = u + a t

- 39.69 = + 20 - 9.8 t

t = 6.09 second

3 0

3 years ago

Measuring the diameter of a specific object might include which pair of SI units

VLD [36.1K]

Well, the diameter of a circle is simply a length, so your measurement will have units of length. We just have to find an answer that has only units of length.

A). gram, second . . . mass and time. That can't be it.

B). kilogram, ampere . . . mass and current. That can't be it.

C). centimeter, meter . . . both lengths. This one is looking good.

D). candela, mole . . . light intensity and some chemical thing. That can't be it.

So it can't be anything else on this list but <em>C</em> .

8 0

3 years ago

What is displacement?

ycow [4]

Answer:

Change in position of an object A vector quantity with unit of distance.

Explanation:

Where is the object going? Final - initial

5 0

3 years ago