Conservation of momentum: total momentum before = total momentum after
Momentum = mass x velocity
So before the collision:
4kg x 8m/s = 32
1kg x 0m/s = 0
32+0=32
Therefore after the collision
4kg x 4.8m/s = 19.2
1kg x βm/s = β
19.2 + β = 32
Therefore β = 12.8 m/s
Answer:
D) Q/2
Explanation:
The relationship between charge Q, capacitance C and voltage drop V across a capacitor is
(1)
In the first part of the problem, we have that the charge stored on the capacitor is Q, when the voltage supplied is V. The capacitance of the parallel-plate capacitor is given by

where
is the vacuum permittivity, A is the area of the plates, d is the separation between the plates.
Later, the voltage of the battery is kept constant, V, while the separation between the plates of the capacitor is doubled:
. The capacitance becomes

And therefore, the new charge stored on the capacitor will be

Answer:
The magnitude of the frictional force is 48.02 N
Explanation:
Mass of box = 20 kg
Weight of the box (Normal reaction) = mass × acceleration due to gravity = 20 ×9.8 = 196 N
Horizontal force applied = 48 N
Coefficient of friction = horizontal force ÷ normal reaction = 48 ÷ 196 = 0.245
Frictional force = coefficient of friction × normal reaction = 0.245 × 196 N = 48.02 N
Yes, momentum, like velocity, has a direction, and is a vector. (even though it isn't mentioned very often in these high-school problems).
Its direction is the same as the direction of the velocity that it's made of.
But the statement is a bit sloppy . . . It's true that momentum has a direction just like velocity has. But neither of them involves "a force".
Velocity is a direction with a SPEED.
Momentum is a direction with a product of (mass) x (velocity).