A 2.0 kg cart has a momentum of 10.0 kg m/s. What is its velocity? A.)22 m/s

B.) 2.0 m/s

C.) 5.0 m/s

D.) 20. m/s

Explanation:

Momentum is the product of mass and velocity. The formula is:

The mass of the cart is 2.0 kilograms. The momentum is 10.0 kg m/s. The velocity is unknown.

Substitute the values into the formula.

We want to solve for the velocity (v). Therefore we must isolate the variable. It is being multiplied and the inverse of multiplication is division. Divide both sides of the equation by 2.0 kg.

The kilograms will cancel each other out.

The velocity is 5 meters per second.

the velocity you are looking for is made up of two parts: horizontally velocity, vh, and its vertical velocity, vv. the actual velocity of the ball will be these two parts added together, and because velocity is a vector then they will need to be added vectorially.  

neglecting air resistance etc etc.,  

the horizontal velocity component will be constant (because there is no accelerating force in the horizontal direction.  

vh = 8 ms-1  

the vertical velocity component has an accelerating force: 'g'.  

using v = u +at where a = g = 9.81 ms-2.  

the vertical component of velocity, vv = 0 + gt = vv =9.81 x 2  

vv = 19.62 ms-1 . the zero appears because the virtical component of velocity at time t=0 is zero. remember, the ball was thrown horizontally.  

how fast it will be moving (it actual path (being a parabola )) will be the vector sum of these two.  

adding vectorally gives: -  

v = sqr root (8^2 + 19.62^2) = sqr root(64+384.9) = 21.18 or 21.2 ms-1

b) 10 minutes

girls stopped for 10 minutes.