Answer:
(a) 
(b)
Explanation:
It is given that,
Force acting on the particle, F = 12 N
Displacement of the particle, 
Magnitude of displacement, 
(a) If the change in the kinetic energy of the particle is +30 J. The work done by the particle is given by :

is the angle between force and the displacement
According to work energy theorem, the charge in kinetic energy of the particle is equal to the work done.
So,



(b) If the change in the kinetic energy of the particle is (-30) J. The work done by the particle is given by :


Hence, this is the required solution.
Answer:
58.8 N
Explanation:
The normal force is calculated as equal to the perpendicular component of the gravitational force.
Thus; N = mg
We are given m = 6 kg
Thus;
N = 6 × 9.8
N = 58.8 N
Thus, magnitude of normal force on the rock = 58.8 N
<span>Density can be calculated and found by dividing the sample's mass by its volume. D=m/v</span>
Answer:
18.24 seconds
Explanation:
First you convert the km/h to m/s, 70km/h=(175/9)m/s,85km/h=(425/18)m/s.
You know it took 10 seconds for the police to reach 85 km/h. Calculate the distance that the car is ahead of the police (175/9)*10=1750/9m. Then by divide 1750/9 with 425/18, you will get the value 8.24. Add the 10 seconds with the 8.24 you will get 18.24 sec which is the total time.
Solution :
When the spacecraft is at halfway point, the distance from the Earth as well as Mars are same. We have to account the masses of the planets. The gravitational force that is exerted by the Earth is greater because of its combined mass with the space probe.
The mass of Earth is greater than the mass of Mars. Therefore, the force of Earth is more than Mars.