For #5 It's helpful to draw a free body diagram so you know which way the forces are acting on the block. 
the weight mg is acting downwards, and you need to find the vertical and horizontal components of mg using sin and cosine. so do 15x9.8xsin40 which is the force. Assuming no friction, this is the only force acting on the block, as the forces on the vertical plane cancel out i.e the normal force and weight of the block.
after, just do F=ma And since you know F and m, solve for a.
        
             
        
        
        
1. Cenozoic ERA
2. Mesozoic ERA
3. Paleozoic ERA
        
             
        
        
        
<h3>Option B</h3><h3>The time constant of a 10 H inductor and a 200 ohm resistor connected in series is 50 millisecond</h3>
<em><u>Solution:</u></em>
Given that,
10 H inductor and a 200 ohm resistor connected in series
To find: time constant
<em><u>The time constant in seconds is given as:</u></em>

Where,
L is the inductance in henry and R is the resistance in ohms

Convert to millisecond
1 second = 1000 millisecond
0.05 second = 0.05 x 1000 = 50 millisecond
Thus time constant is 50 millisecond
 
        
        
        
Answer: the contact force is when you rub the balloon on a surface
Explanation: