Search our library of homework questions

Top answers

All subjects

All levels

A transformer has an input voltage of 4V, an output voltage of 8V and 50 turns on its primary coil. Assuming 100% efficiency, find the number of turns on the secondary coil.

Using Vp/Vs=Np/Ns, we can rearrange to get Ns= (VsNp)/VpSo, Ns = 8*50/4=100 turns.

3099 Views

A projectile is launched from ground level with a speed of 25 m/s at an angle of 42° to the horizontal. What is the horizontal distance from the starting point of the projectile when it hits the ground?

Resolve the vertical velocity of the projectile (25sin42) and use v=u+at where v=-25sin42m/s, u=25sin42m/s, a=-9.8m/s/s to find t. t= (50sin42)/9.8= 3.41sResolve horizontal velocity (25cos42) and multiply...

Answered by Joe W. • Physics tutor

17913 Views

Translate the following text into English

Mes copains vont souvent au jardin public près de l'école parce qu’on peut jouer au foot. C'est inquiétant le nombre de sans-abris qu'on y voit. Nous aimerions pouvoir donner de notre temps pour les aider...

Answered by Joe W. • French tutor

3609 Views

Write 5cos(theta) – 2sin(theta) in the form Rcos(theta + alpha), where R and alpha are constants, R > 0 and 0 <=alpha < 2 π Give the exact value of R and give the value of alpha in radians to 3 decimal places.

Use the formula cos(A+B)=cosAcosB-sinAsinB, Rcos(theta+alpha)=Rcos(alpha)cos(theta)-Rsin(alpha)sin(theta)5=Rcos(alpha)2=Rsin(alpha)tan(alpha)=2/5alpha= 0.381R=sqrt(5^2+2^2)=sqrt(29)So, 5cos(theta) – 2sin(...

Answered by Joe W. • Maths tutor

11673 Views

The equation of the line L1 is y = 3x – 2 The equation of the line L2 is 3y – 9x + 5 = 0 Show that these two lines are parallel.

L1 is in the form y=mx+c where m is the gradient, 3.L2 can be rewritten as 3y=9x-5, then y=3x-(5/3) to reach y=mx+c. So, the gradient of L2 is 3.Therefore, both lines are parallel.

Answered by Joe W. • Maths tutor

4800 Views