Answer:
t = 3 seconds
Explanation:
Given that,
Initial speed, u = 30 m/s
Final speed, v = 0
It slides 45 m to rest.it take the box to come to rest
We need to find how long it take the box to come to rest.
Let a be the acceleration and t is time.

Now finding time.

So, the required time is 3 seconds.
Answer:
Hope this helps you find the answer
Explanation:
The proteins, lipids, and polysaccharides that make up most of the food we eat must be broken down into smaller molecules before our cells can use them—either as a source of energy or as building blocks for other molecules.
Answer:
Nuclear power is presently a sustainable energy source, but could become completely renewable if the source of uranium changed from mined ore to seawater. Since U extracted is continuously replenished through geologic processes, nuclear would become as endless as solar.
Answer:
280 N
Explanation:
acceleration = v2-v1 / time taken = (2-4 )/ 0.05 = -40 m/s^2 ( neg sign indicates slowing down )
force exerted = ma = 7 kg x -40 m/s^2 = - 280 N ( neg sign means opposite direction of initial velocity )
since the 7 kg ball is slowing down, the direction of force will be opposite of the initial velocity , and it will be 280 N
D. a train on a straight track