The compass doesn’t give you the value of the net magnetic field, just the direction. So, how do you get the magnitude of a particular field from this? The trick is to assume the value of the Earth’s magnetic field and the direction of the compass. Let’s assume that at this location on the Earth, the magnetic field is pointing directly North with a horizontal component of about 2 x 10-5 T.
Now suppose that I do something to create a magnetic field in a known direction and perpendicular to the horizontal component of the Earth’s magnetic field. Here is an example where I put a current carrying wire right over the compass needle. Since the compass is underneath the wire, the magnetic field due to the wire will be 90° to the Earth’s magnetic field.
Answer:
21.75 m
Explanation:
t = Time taken for the car to slow down = 0.75 s
u = Initial velocity = 50 m/s
v = Final velocity = 8 m/s
s = Displacement
a = Acceleration
Equation of motion

Acceleration is -56 m/s²

The distance covered in the 0.75 seconds is 21.75 m
Answer:

Explanation:
If the collision is elastic and exactly head-on, then we can use the law of momentum conservation for the motion of the 2 balls
Before the collision

After the collision

So using the law of momentum conservation


We can solve for the speed of ball 1 post collision in terms of others:

Their kinetic energy is also conserved before and after collision


From here we can plug in 





