Show that 2sinøcosø =sin2ø

One beam of electrons moves at right angles to a magnetic field. the force on these electrons is 4.9 x 10-14 newtons. a second b

diamong [38]

Below are the choices that can be found elsewhere:

A. (4.9 × 10-14 newtons) · tan(30°)
B. (4.9 × 10-14 newtons) · sin(30°) 
C. (4.9 × 10-14 newtons) · cos(30°) 
D. (4.9 × 10-14 newtons) · arctan(30°) 
E. (4.9 × 10-14 newtons) · arccos(30°)

Force is proportional to the angle made by the velocity with respect to the magnetic field. It is maximum when velocity is perpendicular to the magnetic field and minimum when the velocity is parallel to the magnetic field. It is proportional to sin of the angle. In this problem it will be proportional to sin(30)

7 0

3 years ago

A person is standing on and facing the front of a stationary skateboard while holding a construction brick. The mass of the pers

jek_recluse [69]

Answer:

0.74 m/s

Explanation:

From the question,

We apply the law of conservation of momentum,

Total momentum before collision = Total momentum after collision.

Since the skateboard, the person and the brick where stationary, therefore, the total momentum before collision is 0

0 = Total momentum after collision

(m+M)V + m'v = 0

Where m = mass of the skateboard, M = mass of the person, m' = mass of the brick, V = recoil velocity of the person and the skateboard, v = velocity of the brick

make V the subject of the equation above

V = -m'v/(m+M)................... Equation 1

Given: m = 4.10 kg, M = 68.0 kg, m' = 2.50 kg, v = 21.0 m/s.

Substitute these values into equation 1

V = -(2.5×21)/(68+2.5)

V = 52.50/70.5

V = 0.74 m/s

4 0

3 years ago

A driver sets out on a journey. for the first half of the distance she drives at the leisurely pace of 30 mi/h; during the secon

Gemiola [76]

The average speed of a moving object is the rate of change of a certain distance with respect with time. It is equal to the total distance that was traveled by the object over the total time it takes to travel that distance. For this problem we need to assume that the total distance that was traveled would be equal to 120 miles. So, for the first half of the distance or 60 miles at a speed of 30 miles per hour, the time taken would be two hours. For the remaining 60 miles at a speed of 60 miles per hour, 1 hour is total time traveled. So, we calculate the average speed as follows:

Average speed = total distance / total time
Average speed = 120 miles / 2 hr + 1 hr
Average speed = 40 mi / hr

5 0

4 years ago

Diya visited a tailor shop and bought home three cuttings of fabric A,B and C to study their properties. Diya tried burning the

andreev551 [17]

Answer:

Rayon

Wool

Silk Yarn

Explanation:

Rayon

This is Fabric A. Rayon basically burns very quickly even quicker than fabrics like cotton and linen. Its ash is gray in color. The rayon fabric smells of burning paper when it is burnt.

Wool:

This is Fabric B. Wool is basically hard to ignite. It burns slowly. Its ash is dark in color. The wool fabric smells of burning hair when it is burnt.

Silk Yarn:

This is Fabric C. The silk yarn shrinks from the flame when it is burned. It has a grayish black ash. The silk yarn fabric smells burnt meat of when it is burnt.

3 0

3 years ago

Elect the correct answer. Two identical projectiles, A and B, are launched with the same initial velocity, but the angle of laun

allsm [11]

Answer:

A. The range of A and B are equal.

Explanation:

Let u be the initial speed of both the projectile.

The gravitational force acting in the projectile is in the downward direction, sp the speed of the projectile in the horizontal direction remains constant and equals to the initial horizontal speed.

For projectile, a projectile having initial velocity u at an angle \theta with the horizontal direction,

The speed in the horizontal direction $= u\cos\theta$

and the speed in the vertical direction is $= u\sin\theta$ upward.

For A:

The speed in the horizontal direction $= u\cos75^{\circ}$

and the speed in the vertical direction is $= u\sin75^{\circ}$ upward.

For B:

The speed in the horizontal direction $= u\cos15^{\circ}$

and the speed in the vertical direction is $= u\sin15^{\circ}$ upward.

Let $t_A$ and $t_B$ are the time of flight for projectile A and B respectively.

As the range is the horizontal distance traveled by the projectile, so

The range for the projectile A $= u\cos75^{\circ}\times t_A\cdots(i)$

The range for the projectile B = $u\cos15^{\circ}\times t_B\cdots(ii)$

At the highest point, the vertical velocity is 0.

Bu using the equation of motion $v^2=u^2 +2a s.$

Here, the final velocity v=0, the initial velocity $u = u \sin \theta$ , h= vertical distance up to the highest point, and $a= -g$ (as per sign convention).